cache.cc revision 13945
112027Sjungma@eit.uni-kl.de/* 212027Sjungma@eit.uni-kl.de * Copyright (c) 2010-2019 ARM Limited 312027Sjungma@eit.uni-kl.de * All rights reserved. 412027Sjungma@eit.uni-kl.de * 512027Sjungma@eit.uni-kl.de * The license below extends only to copyright in the software and shall 612027Sjungma@eit.uni-kl.de * not be construed as granting a license to any other intellectual 712027Sjungma@eit.uni-kl.de * property including but not limited to intellectual property relating 812027Sjungma@eit.uni-kl.de * to a hardware implementation of the functionality of the software 912027Sjungma@eit.uni-kl.de * licensed hereunder. You may use the software subject to the license 1012027Sjungma@eit.uni-kl.de * terms below provided that you ensure that this notice is replicated 1112027Sjungma@eit.uni-kl.de * unmodified and in its entirety in all distributions of the software, 1212027Sjungma@eit.uni-kl.de * modified or unmodified, in source code or in binary form. 1312027Sjungma@eit.uni-kl.de * 1412027Sjungma@eit.uni-kl.de * Copyright (c) 2002-2005 The Regents of The University of Michigan 1512027Sjungma@eit.uni-kl.de * Copyright (c) 2010,2015 Advanced Micro Devices, Inc. 1612027Sjungma@eit.uni-kl.de * All rights reserved. 1712027Sjungma@eit.uni-kl.de * 1812027Sjungma@eit.uni-kl.de * Redistribution and use in source and binary forms, with or without 1912027Sjungma@eit.uni-kl.de * modification, are permitted provided that the following conditions are 2012027Sjungma@eit.uni-kl.de * met: redistributions of source code must retain the above copyright 2112027Sjungma@eit.uni-kl.de * notice, this list of conditions and the following disclaimer; 2212027Sjungma@eit.uni-kl.de * redistributions in binary form must reproduce the above copyright 2312027Sjungma@eit.uni-kl.de * notice, this list of conditions and the following disclaimer in the 2412027Sjungma@eit.uni-kl.de * documentation and/or other materials provided with the distribution; 2512027Sjungma@eit.uni-kl.de * neither the name of the copyright holders nor the names of its 2612027Sjungma@eit.uni-kl.de * contributors may be used to endorse or promote products derived from 2712027Sjungma@eit.uni-kl.de * this software without specific prior written permission. 2812027Sjungma@eit.uni-kl.de * 2912027Sjungma@eit.uni-kl.de * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 3012027Sjungma@eit.uni-kl.de * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 3112027Sjungma@eit.uni-kl.de * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 3212027Sjungma@eit.uni-kl.de * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 3312027Sjungma@eit.uni-kl.de * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 3412027Sjungma@eit.uni-kl.de * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 3512027Sjungma@eit.uni-kl.de * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 3612027Sjungma@eit.uni-kl.de * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 3712027Sjungma@eit.uni-kl.de * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 3812027Sjungma@eit.uni-kl.de * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 3912027Sjungma@eit.uni-kl.de * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 4012027Sjungma@eit.uni-kl.de * 4112027Sjungma@eit.uni-kl.de * Authors: Erik Hallnor 4212027Sjungma@eit.uni-kl.de * Dave Greene 4312027Sjungma@eit.uni-kl.de * Nathan Binkert 4412027Sjungma@eit.uni-kl.de * Steve Reinhardt 4512027Sjungma@eit.uni-kl.de * Ron Dreslinski 4612027Sjungma@eit.uni-kl.de * Andreas Sandberg 4712027Sjungma@eit.uni-kl.de * Nikos Nikoleris 4812027Sjungma@eit.uni-kl.de */ 4912027Sjungma@eit.uni-kl.de 5012027Sjungma@eit.uni-kl.de/** 5112027Sjungma@eit.uni-kl.de * @file 5212027Sjungma@eit.uni-kl.de * Cache definitions. 5312027Sjungma@eit.uni-kl.de */ 5412027Sjungma@eit.uni-kl.de 5512027Sjungma@eit.uni-kl.de#include "mem/cache/cache.hh" 5612027Sjungma@eit.uni-kl.de 5712027Sjungma@eit.uni-kl.de#include <cassert> 5812027Sjungma@eit.uni-kl.de 5912027Sjungma@eit.uni-kl.de#include "base/compiler.hh" 6012027Sjungma@eit.uni-kl.de#include "base/logging.hh" 6112027Sjungma@eit.uni-kl.de#include "base/trace.hh" 6212027Sjungma@eit.uni-kl.de#include "base/types.hh" 6312027Sjungma@eit.uni-kl.de#include "debug/Cache.hh" 6412027Sjungma@eit.uni-kl.de#include "debug/CacheTags.hh" 6512027Sjungma@eit.uni-kl.de#include "debug/CacheVerbose.hh" 6612027Sjungma@eit.uni-kl.de#include "enums/Clusivity.hh" 6712027Sjungma@eit.uni-kl.de#include "mem/cache/cache_blk.hh" 6812027Sjungma@eit.uni-kl.de#include "mem/cache/mshr.hh" 6912027Sjungma@eit.uni-kl.de#include "mem/cache/tags/base.hh" 7012027Sjungma@eit.uni-kl.de#include "mem/cache/write_queue_entry.hh" 7112027Sjungma@eit.uni-kl.de#include "mem/request.hh" 7212027Sjungma@eit.uni-kl.de#include "params/Cache.hh" 7312027Sjungma@eit.uni-kl.de 7412027Sjungma@eit.uni-kl.deCache::Cache(const CacheParams *p) 7512027Sjungma@eit.uni-kl.de : BaseCache(p, p->system->cacheLineSize()), 7612027Sjungma@eit.uni-kl.de doFastWrites(true) 7712027Sjungma@eit.uni-kl.de{ 7812027Sjungma@eit.uni-kl.de} 7912027Sjungma@eit.uni-kl.de 8012027Sjungma@eit.uni-kl.devoid 8112027Sjungma@eit.uni-kl.deCache::satisfyRequest(PacketPtr pkt, CacheBlk *blk, 8212027Sjungma@eit.uni-kl.de bool deferred_response, bool pending_downgrade) 8312027Sjungma@eit.uni-kl.de{ 8412027Sjungma@eit.uni-kl.de BaseCache::satisfyRequest(pkt, blk); 8512027Sjungma@eit.uni-kl.de 8612027Sjungma@eit.uni-kl.de if (pkt->isRead()) { 8712027Sjungma@eit.uni-kl.de // determine if this read is from a (coherent) cache or not 8812027Sjungma@eit.uni-kl.de if (pkt->fromCache()) { 8912027Sjungma@eit.uni-kl.de assert(pkt->getSize() == blkSize); 9012027Sjungma@eit.uni-kl.de // special handling for coherent block requests from 9112027Sjungma@eit.uni-kl.de // upper-level caches 9212027Sjungma@eit.uni-kl.de if (pkt->needsWritable()) { 9312027Sjungma@eit.uni-kl.de // sanity check 9412027Sjungma@eit.uni-kl.de assert(pkt->cmd == MemCmd::ReadExReq || 9512027Sjungma@eit.uni-kl.de pkt->cmd == MemCmd::SCUpgradeFailReq); 9612027Sjungma@eit.uni-kl.de assert(!pkt->hasSharers()); 9712027Sjungma@eit.uni-kl.de 9812027Sjungma@eit.uni-kl.de // if we have a dirty copy, make sure the recipient 9912027Sjungma@eit.uni-kl.de // keeps it marked dirty (in the modified state) 10012027Sjungma@eit.uni-kl.de if (blk->isDirty()) { 10112027Sjungma@eit.uni-kl.de pkt->setCacheResponding(); 10212027Sjungma@eit.uni-kl.de blk->status &= ~BlkDirty; 10312027Sjungma@eit.uni-kl.de } 10412027Sjungma@eit.uni-kl.de } else if (blk->isWritable() && !pending_downgrade && 10512027Sjungma@eit.uni-kl.de !pkt->hasSharers() && 10612027Sjungma@eit.uni-kl.de pkt->cmd != MemCmd::ReadCleanReq) { 10712027Sjungma@eit.uni-kl.de // we can give the requester a writable copy on a read 10812027Sjungma@eit.uni-kl.de // request if: 10912027Sjungma@eit.uni-kl.de // - we have a writable copy at this level (& below) 11012027Sjungma@eit.uni-kl.de // - we don't have a pending snoop from below 11112027Sjungma@eit.uni-kl.de // signaling another read request 11212027Sjungma@eit.uni-kl.de // - no other cache above has a copy (otherwise it 11312027Sjungma@eit.uni-kl.de // would have set hasSharers flag when 11412027Sjungma@eit.uni-kl.de // snooping the packet) 11512027Sjungma@eit.uni-kl.de // - the read has explicitly asked for a clean 11612027Sjungma@eit.uni-kl.de // copy of the line 11712027Sjungma@eit.uni-kl.de if (blk->isDirty()) { 11812027Sjungma@eit.uni-kl.de // special considerations if we're owner: 11912027Sjungma@eit.uni-kl.de if (!deferred_response) { 12012027Sjungma@eit.uni-kl.de // respond with the line in Modified state 12112027Sjungma@eit.uni-kl.de // (cacheResponding set, hasSharers not set) 12212027Sjungma@eit.uni-kl.de pkt->setCacheResponding(); 12312027Sjungma@eit.uni-kl.de 12412027Sjungma@eit.uni-kl.de // if this cache is mostly inclusive, we 12512027Sjungma@eit.uni-kl.de // keep the block in the Exclusive state, 12612027Sjungma@eit.uni-kl.de // and pass it upwards as Modified 12712027Sjungma@eit.uni-kl.de // (writable and dirty), hence we have 12812027Sjungma@eit.uni-kl.de // multiple caches, all on the same path 12912027Sjungma@eit.uni-kl.de // towards memory, all considering the 13012027Sjungma@eit.uni-kl.de // same block writable, but only one 13112027Sjungma@eit.uni-kl.de // considering it Modified 13212027Sjungma@eit.uni-kl.de 13312027Sjungma@eit.uni-kl.de // we get away with multiple caches (on 13412027Sjungma@eit.uni-kl.de // the same path to memory) considering 13512027Sjungma@eit.uni-kl.de // the block writeable as we always enter 13612027Sjungma@eit.uni-kl.de // the cache hierarchy through a cache, 13712027Sjungma@eit.uni-kl.de // and first snoop upwards in all other 13812027Sjungma@eit.uni-kl.de // branches 13912027Sjungma@eit.uni-kl.de blk->status &= ~BlkDirty; 14012027Sjungma@eit.uni-kl.de } else { 14112027Sjungma@eit.uni-kl.de // if we're responding after our own miss, 14212027Sjungma@eit.uni-kl.de // there's a window where the recipient didn't 14312027Sjungma@eit.uni-kl.de // know it was getting ownership and may not 14412027Sjungma@eit.uni-kl.de // have responded to snoops correctly, so we 14512027Sjungma@eit.uni-kl.de // have to respond with a shared line 14612027Sjungma@eit.uni-kl.de pkt->setHasSharers(); 14712027Sjungma@eit.uni-kl.de } 14812027Sjungma@eit.uni-kl.de } 14912027Sjungma@eit.uni-kl.de } else { 15012027Sjungma@eit.uni-kl.de // otherwise only respond with a shared copy 15112027Sjungma@eit.uni-kl.de pkt->setHasSharers(); 15212027Sjungma@eit.uni-kl.de } 15312027Sjungma@eit.uni-kl.de } 15412027Sjungma@eit.uni-kl.de } 15512027Sjungma@eit.uni-kl.de} 15612027Sjungma@eit.uni-kl.de 15712027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 15812027Sjungma@eit.uni-kl.de// 15912027Sjungma@eit.uni-kl.de// Access path: requests coming in from the CPU side 16012027Sjungma@eit.uni-kl.de// 16112027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 16212027Sjungma@eit.uni-kl.de 16312027Sjungma@eit.uni-kl.debool 16412027Sjungma@eit.uni-kl.deCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat, 16512027Sjungma@eit.uni-kl.de PacketList &writebacks) 16612027Sjungma@eit.uni-kl.de{ 16712027Sjungma@eit.uni-kl.de 16812027Sjungma@eit.uni-kl.de if (pkt->req->isUncacheable()) { 16912027Sjungma@eit.uni-kl.de assert(pkt->isRequest()); 17012027Sjungma@eit.uni-kl.de 17112027Sjungma@eit.uni-kl.de chatty_assert(!(isReadOnly && pkt->isWrite()), 17212027Sjungma@eit.uni-kl.de "Should never see a write in a read-only cache %s\n", 17312027Sjungma@eit.uni-kl.de name()); 17412027Sjungma@eit.uni-kl.de 17512027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s for %s\n", __func__, pkt->print()); 17612027Sjungma@eit.uni-kl.de 17712027Sjungma@eit.uni-kl.de // flush and invalidate any existing block 17812027Sjungma@eit.uni-kl.de CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure())); 17912027Sjungma@eit.uni-kl.de if (old_blk && old_blk->isValid()) { 18012027Sjungma@eit.uni-kl.de BaseCache::evictBlock(old_blk, writebacks); 18112027Sjungma@eit.uni-kl.de } 18212027Sjungma@eit.uni-kl.de 18312027Sjungma@eit.uni-kl.de blk = nullptr; 18412027Sjungma@eit.uni-kl.de // lookupLatency is the latency in case the request is uncacheable. 18512027Sjungma@eit.uni-kl.de lat = lookupLatency; 18612027Sjungma@eit.uni-kl.de return false; 18712027Sjungma@eit.uni-kl.de } 18812027Sjungma@eit.uni-kl.de 18912027Sjungma@eit.uni-kl.de return BaseCache::access(pkt, blk, lat, writebacks); 19012027Sjungma@eit.uni-kl.de} 19112027Sjungma@eit.uni-kl.de 19212027Sjungma@eit.uni-kl.devoid 19312027Sjungma@eit.uni-kl.deCache::doWritebacks(PacketList& writebacks, Tick forward_time) 19412027Sjungma@eit.uni-kl.de{ 19512027Sjungma@eit.uni-kl.de while (!writebacks.empty()) { 19612027Sjungma@eit.uni-kl.de PacketPtr wbPkt = writebacks.front(); 19712027Sjungma@eit.uni-kl.de // We use forwardLatency here because we are copying writebacks to 19812027Sjungma@eit.uni-kl.de // write buffer. 19912027Sjungma@eit.uni-kl.de 20012027Sjungma@eit.uni-kl.de // Call isCachedAbove for Writebacks, CleanEvicts and 20112027Sjungma@eit.uni-kl.de // WriteCleans to discover if the block is cached above. 20212027Sjungma@eit.uni-kl.de if (isCachedAbove(wbPkt)) { 20312027Sjungma@eit.uni-kl.de if (wbPkt->cmd == MemCmd::CleanEvict) { 20412027Sjungma@eit.uni-kl.de // Delete CleanEvict because cached copies exist above. The 20512027Sjungma@eit.uni-kl.de // packet destructor will delete the request object because 20612027Sjungma@eit.uni-kl.de // this is a non-snoop request packet which does not require a 20712027Sjungma@eit.uni-kl.de // response. 20812027Sjungma@eit.uni-kl.de delete wbPkt; 20912027Sjungma@eit.uni-kl.de } else if (wbPkt->cmd == MemCmd::WritebackClean) { 21012027Sjungma@eit.uni-kl.de // clean writeback, do not send since the block is 21112027Sjungma@eit.uni-kl.de // still cached above 21212027Sjungma@eit.uni-kl.de assert(writebackClean); 21312027Sjungma@eit.uni-kl.de delete wbPkt; 21412027Sjungma@eit.uni-kl.de } else { 21512027Sjungma@eit.uni-kl.de assert(wbPkt->cmd == MemCmd::WritebackDirty || 21612027Sjungma@eit.uni-kl.de wbPkt->cmd == MemCmd::WriteClean); 21712027Sjungma@eit.uni-kl.de // Set BLOCK_CACHED flag in Writeback and send below, so that 21812027Sjungma@eit.uni-kl.de // the Writeback does not reset the bit corresponding to this 21912027Sjungma@eit.uni-kl.de // address in the snoop filter below. 22012027Sjungma@eit.uni-kl.de wbPkt->setBlockCached(); 22112027Sjungma@eit.uni-kl.de allocateWriteBuffer(wbPkt, forward_time); 22212027Sjungma@eit.uni-kl.de } 22312027Sjungma@eit.uni-kl.de } else { 22412027Sjungma@eit.uni-kl.de // If the block is not cached above, send packet below. Both 22512027Sjungma@eit.uni-kl.de // CleanEvict and Writeback with BLOCK_CACHED flag cleared will 22612027Sjungma@eit.uni-kl.de // reset the bit corresponding to this address in the snoop filter 22712027Sjungma@eit.uni-kl.de // below. 22812027Sjungma@eit.uni-kl.de allocateWriteBuffer(wbPkt, forward_time); 22912027Sjungma@eit.uni-kl.de } 23012027Sjungma@eit.uni-kl.de writebacks.pop_front(); 23112027Sjungma@eit.uni-kl.de } 23212027Sjungma@eit.uni-kl.de} 23312027Sjungma@eit.uni-kl.de 23412027Sjungma@eit.uni-kl.devoid 23512027Sjungma@eit.uni-kl.deCache::doWritebacksAtomic(PacketList& writebacks) 23612027Sjungma@eit.uni-kl.de{ 23712027Sjungma@eit.uni-kl.de while (!writebacks.empty()) { 23812027Sjungma@eit.uni-kl.de PacketPtr wbPkt = writebacks.front(); 23912027Sjungma@eit.uni-kl.de // Call isCachedAbove for both Writebacks and CleanEvicts. If 24012027Sjungma@eit.uni-kl.de // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks 24112027Sjungma@eit.uni-kl.de // and discard CleanEvicts. 24212027Sjungma@eit.uni-kl.de if (isCachedAbove(wbPkt, false)) { 24312027Sjungma@eit.uni-kl.de if (wbPkt->cmd == MemCmd::WritebackDirty || 24412027Sjungma@eit.uni-kl.de wbPkt->cmd == MemCmd::WriteClean) { 24512027Sjungma@eit.uni-kl.de // Set BLOCK_CACHED flag in Writeback and send below, 24612027Sjungma@eit.uni-kl.de // so that the Writeback does not reset the bit 24712027Sjungma@eit.uni-kl.de // corresponding to this address in the snoop filter 24812027Sjungma@eit.uni-kl.de // below. We can discard CleanEvicts because cached 24912027Sjungma@eit.uni-kl.de // copies exist above. Atomic mode isCachedAbove 25012027Sjungma@eit.uni-kl.de // modifies packet to set BLOCK_CACHED flag 25112027Sjungma@eit.uni-kl.de memSidePort.sendAtomic(wbPkt); 25212027Sjungma@eit.uni-kl.de } 25312027Sjungma@eit.uni-kl.de } else { 25412027Sjungma@eit.uni-kl.de // If the block is not cached above, send packet below. Both 25512027Sjungma@eit.uni-kl.de // CleanEvict and Writeback with BLOCK_CACHED flag cleared will 25612027Sjungma@eit.uni-kl.de // reset the bit corresponding to this address in the snoop filter 25712027Sjungma@eit.uni-kl.de // below. 25812027Sjungma@eit.uni-kl.de memSidePort.sendAtomic(wbPkt); 25912027Sjungma@eit.uni-kl.de } 26012027Sjungma@eit.uni-kl.de writebacks.pop_front(); 26112027Sjungma@eit.uni-kl.de // In case of CleanEvicts, the packet destructor will delete the 26212027Sjungma@eit.uni-kl.de // request object because this is a non-snoop request packet which 26312027Sjungma@eit.uni-kl.de // does not require a response. 26412027Sjungma@eit.uni-kl.de delete wbPkt; 26512027Sjungma@eit.uni-kl.de } 26612027Sjungma@eit.uni-kl.de} 26712027Sjungma@eit.uni-kl.de 26812027Sjungma@eit.uni-kl.de 26912027Sjungma@eit.uni-kl.devoid 27012027Sjungma@eit.uni-kl.deCache::recvTimingSnoopResp(PacketPtr pkt) 27112027Sjungma@eit.uni-kl.de{ 27212027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s for %s\n", __func__, pkt->print()); 27312027Sjungma@eit.uni-kl.de 27412027Sjungma@eit.uni-kl.de // determine if the response is from a snoop request we created 27512027Sjungma@eit.uni-kl.de // (in which case it should be in the outstandingSnoop), or if we 27612027Sjungma@eit.uni-kl.de // merely forwarded someone else's snoop request 27712027Sjungma@eit.uni-kl.de const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) == 27812027Sjungma@eit.uni-kl.de outstandingSnoop.end(); 27912027Sjungma@eit.uni-kl.de 28012027Sjungma@eit.uni-kl.de if (!forwardAsSnoop) { 28112027Sjungma@eit.uni-kl.de // the packet came from this cache, so sink it here and do not 28212027Sjungma@eit.uni-kl.de // forward it 28312027Sjungma@eit.uni-kl.de assert(pkt->cmd == MemCmd::HardPFResp); 28412027Sjungma@eit.uni-kl.de 28512027Sjungma@eit.uni-kl.de outstandingSnoop.erase(pkt->req); 28612027Sjungma@eit.uni-kl.de 28712027Sjungma@eit.uni-kl.de DPRINTF(Cache, "Got prefetch response from above for addr " 28812027Sjungma@eit.uni-kl.de "%#llx (%s)\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns"); 28912027Sjungma@eit.uni-kl.de recvTimingResp(pkt); 29012027Sjungma@eit.uni-kl.de return; 29112027Sjungma@eit.uni-kl.de } 29212027Sjungma@eit.uni-kl.de 29312027Sjungma@eit.uni-kl.de // forwardLatency is set here because there is a response from an 29412027Sjungma@eit.uni-kl.de // upper level cache. 29512027Sjungma@eit.uni-kl.de // To pay the delay that occurs if the packet comes from the bus, 29612027Sjungma@eit.uni-kl.de // we charge also headerDelay. 29712027Sjungma@eit.uni-kl.de Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay; 29812027Sjungma@eit.uni-kl.de // Reset the timing of the packet. 29912027Sjungma@eit.uni-kl.de pkt->headerDelay = pkt->payloadDelay = 0; 30012027Sjungma@eit.uni-kl.de memSidePort.schedTimingSnoopResp(pkt, snoop_resp_time); 30112027Sjungma@eit.uni-kl.de} 30212027Sjungma@eit.uni-kl.de 30312027Sjungma@eit.uni-kl.devoid 30412027Sjungma@eit.uni-kl.deCache::promoteWholeLineWrites(PacketPtr pkt) 30512027Sjungma@eit.uni-kl.de{ 30612027Sjungma@eit.uni-kl.de // Cache line clearing instructions 30712027Sjungma@eit.uni-kl.de if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) && 30812027Sjungma@eit.uni-kl.de (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) { 30912027Sjungma@eit.uni-kl.de pkt->cmd = MemCmd::WriteLineReq; 31012027Sjungma@eit.uni-kl.de DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n"); 31112027Sjungma@eit.uni-kl.de } 31212027Sjungma@eit.uni-kl.de} 31312027Sjungma@eit.uni-kl.de 31412027Sjungma@eit.uni-kl.devoid 31512027Sjungma@eit.uni-kl.deCache::handleTimingReqHit(PacketPtr pkt, CacheBlk *blk, Tick request_time) 31612027Sjungma@eit.uni-kl.de{ 31712027Sjungma@eit.uni-kl.de // should never be satisfying an uncacheable access as we 31812027Sjungma@eit.uni-kl.de // flush and invalidate any existing block as part of the 31912027Sjungma@eit.uni-kl.de // lookup 32012027Sjungma@eit.uni-kl.de assert(!pkt->req->isUncacheable()); 32112027Sjungma@eit.uni-kl.de 32212027Sjungma@eit.uni-kl.de BaseCache::handleTimingReqHit(pkt, blk, request_time); 32312027Sjungma@eit.uni-kl.de} 32412027Sjungma@eit.uni-kl.de 32512027Sjungma@eit.uni-kl.devoid 32612027Sjungma@eit.uni-kl.deCache::handleTimingReqMiss(PacketPtr pkt, CacheBlk *blk, Tick forward_time, 32712027Sjungma@eit.uni-kl.de Tick request_time) 32812027Sjungma@eit.uni-kl.de{ 32912027Sjungma@eit.uni-kl.de if (pkt->req->isUncacheable()) { 33012027Sjungma@eit.uni-kl.de // ignore any existing MSHR if we are dealing with an 33112027Sjungma@eit.uni-kl.de // uncacheable request 33212027Sjungma@eit.uni-kl.de 33312027Sjungma@eit.uni-kl.de // should have flushed and have no valid block 33412027Sjungma@eit.uni-kl.de assert(!blk || !blk->isValid()); 33512027Sjungma@eit.uni-kl.de 33612027Sjungma@eit.uni-kl.de mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++; 33712027Sjungma@eit.uni-kl.de 33812027Sjungma@eit.uni-kl.de if (pkt->isWrite()) { 33912027Sjungma@eit.uni-kl.de allocateWriteBuffer(pkt, forward_time); 34012027Sjungma@eit.uni-kl.de } else { 34112027Sjungma@eit.uni-kl.de assert(pkt->isRead()); 34212027Sjungma@eit.uni-kl.de 34312027Sjungma@eit.uni-kl.de // uncacheable accesses always allocate a new MSHR 34412027Sjungma@eit.uni-kl.de 34512027Sjungma@eit.uni-kl.de // Here we are using forward_time, modelling the latency of 34612027Sjungma@eit.uni-kl.de // a miss (outbound) just as forwardLatency, neglecting the 34712027Sjungma@eit.uni-kl.de // lookupLatency component. 34812027Sjungma@eit.uni-kl.de allocateMissBuffer(pkt, forward_time); 34912027Sjungma@eit.uni-kl.de } 35012027Sjungma@eit.uni-kl.de 35112027Sjungma@eit.uni-kl.de return; 35212027Sjungma@eit.uni-kl.de } 35312027Sjungma@eit.uni-kl.de 35412027Sjungma@eit.uni-kl.de Addr blk_addr = pkt->getBlockAddr(blkSize); 35512027Sjungma@eit.uni-kl.de 35612027Sjungma@eit.uni-kl.de MSHR *mshr = mshrQueue.findMatch(blk_addr, pkt->isSecure()); 35712027Sjungma@eit.uni-kl.de 35812027Sjungma@eit.uni-kl.de // Software prefetch handling: 35912027Sjungma@eit.uni-kl.de // To keep the core from waiting on data it won't look at 36012027Sjungma@eit.uni-kl.de // anyway, send back a response with dummy data. Miss handling 36112027Sjungma@eit.uni-kl.de // will continue asynchronously. Unfortunately, the core will 36212027Sjungma@eit.uni-kl.de // insist upon freeing original Packet/Request, so we have to 36312027Sjungma@eit.uni-kl.de // create a new pair with a different lifecycle. Note that this 36412027Sjungma@eit.uni-kl.de // processing happens before any MSHR munging on the behalf of 36512027Sjungma@eit.uni-kl.de // this request because this new Request will be the one stored 36612027Sjungma@eit.uni-kl.de // into the MSHRs, not the original. 36712027Sjungma@eit.uni-kl.de if (pkt->cmd.isSWPrefetch()) { 36812027Sjungma@eit.uni-kl.de assert(pkt->needsResponse()); 36912027Sjungma@eit.uni-kl.de assert(pkt->req->hasPaddr()); 37012027Sjungma@eit.uni-kl.de assert(!pkt->req->isUncacheable()); 37112027Sjungma@eit.uni-kl.de 37212027Sjungma@eit.uni-kl.de // There's no reason to add a prefetch as an additional target 37312027Sjungma@eit.uni-kl.de // to an existing MSHR. If an outstanding request is already 37412027Sjungma@eit.uni-kl.de // in progress, there is nothing for the prefetch to do. 37512027Sjungma@eit.uni-kl.de // If this is the case, we don't even create a request at all. 37612027Sjungma@eit.uni-kl.de PacketPtr pf = nullptr; 37712027Sjungma@eit.uni-kl.de 37812027Sjungma@eit.uni-kl.de if (!mshr) { 37912027Sjungma@eit.uni-kl.de // copy the request and create a new SoftPFReq packet 38012027Sjungma@eit.uni-kl.de RequestPtr req = std::make_shared<Request>(pkt->req->getPaddr(), 38112027Sjungma@eit.uni-kl.de pkt->req->getSize(), 38212027Sjungma@eit.uni-kl.de pkt->req->getFlags(), 38312027Sjungma@eit.uni-kl.de pkt->req->masterId()); 38412027Sjungma@eit.uni-kl.de pf = new Packet(req, pkt->cmd); 38512027Sjungma@eit.uni-kl.de pf->allocate(); 38612027Sjungma@eit.uni-kl.de assert(pf->matchAddr(pkt)); 38712027Sjungma@eit.uni-kl.de assert(pf->getSize() == pkt->getSize()); 38812027Sjungma@eit.uni-kl.de } 38912027Sjungma@eit.uni-kl.de 39012027Sjungma@eit.uni-kl.de pkt->makeTimingResponse(); 39112027Sjungma@eit.uni-kl.de 39212027Sjungma@eit.uni-kl.de // request_time is used here, taking into account lat and the delay 39312027Sjungma@eit.uni-kl.de // charged if the packet comes from the xbar. 39412027Sjungma@eit.uni-kl.de cpuSidePort.schedTimingResp(pkt, request_time); 39512027Sjungma@eit.uni-kl.de 39612027Sjungma@eit.uni-kl.de // If an outstanding request is in progress (we found an 39712027Sjungma@eit.uni-kl.de // MSHR) this is set to null 39812027Sjungma@eit.uni-kl.de pkt = pf; 39912027Sjungma@eit.uni-kl.de } 40012027Sjungma@eit.uni-kl.de 40112027Sjungma@eit.uni-kl.de BaseCache::handleTimingReqMiss(pkt, mshr, blk, forward_time, request_time); 40212027Sjungma@eit.uni-kl.de} 40312027Sjungma@eit.uni-kl.de 40412027Sjungma@eit.uni-kl.devoid 40512027Sjungma@eit.uni-kl.deCache::recvTimingReq(PacketPtr pkt) 40612027Sjungma@eit.uni-kl.de{ 40712027Sjungma@eit.uni-kl.de DPRINTF(CacheTags, "%s tags:\n%s\n", __func__, tags->print()); 40812027Sjungma@eit.uni-kl.de 40912027Sjungma@eit.uni-kl.de promoteWholeLineWrites(pkt); 41012027Sjungma@eit.uni-kl.de 41112027Sjungma@eit.uni-kl.de if (pkt->cacheResponding()) { 41212027Sjungma@eit.uni-kl.de // a cache above us (but not where the packet came from) is 41312027Sjungma@eit.uni-kl.de // responding to the request, in other words it has the line 41412027Sjungma@eit.uni-kl.de // in Modified or Owned state 41512027Sjungma@eit.uni-kl.de DPRINTF(Cache, "Cache above responding to %s: not responding\n", 41612027Sjungma@eit.uni-kl.de pkt->print()); 41712027Sjungma@eit.uni-kl.de 41812027Sjungma@eit.uni-kl.de // if the packet needs the block to be writable, and the cache 41912027Sjungma@eit.uni-kl.de // that has promised to respond (setting the cache responding 42012027Sjungma@eit.uni-kl.de // flag) is not providing writable (it is in Owned rather than 42112027Sjungma@eit.uni-kl.de // the Modified state), we know that there may be other Shared 42212027Sjungma@eit.uni-kl.de // copies in the system; go out and invalidate them all 42312027Sjungma@eit.uni-kl.de assert(pkt->needsWritable() && !pkt->responderHadWritable()); 42412027Sjungma@eit.uni-kl.de 42512027Sjungma@eit.uni-kl.de // an upstream cache that had the line in Owned state 42612027Sjungma@eit.uni-kl.de // (dirty, but not writable), is responding and thus 42712027Sjungma@eit.uni-kl.de // transferring the dirty line from one branch of the 42812027Sjungma@eit.uni-kl.de // cache hierarchy to another 42912027Sjungma@eit.uni-kl.de 43012027Sjungma@eit.uni-kl.de // send out an express snoop and invalidate all other 43112027Sjungma@eit.uni-kl.de // copies (snooping a packet that needs writable is the 43212027Sjungma@eit.uni-kl.de // same as an invalidation), thus turning the Owned line 43312027Sjungma@eit.uni-kl.de // into a Modified line, note that we don't invalidate the 43412027Sjungma@eit.uni-kl.de // block in the current cache or any other cache on the 43512027Sjungma@eit.uni-kl.de // path to memory 43612027Sjungma@eit.uni-kl.de 43712027Sjungma@eit.uni-kl.de // create a downstream express snoop with cleared packet 43812027Sjungma@eit.uni-kl.de // flags, there is no need to allocate any data as the 43912027Sjungma@eit.uni-kl.de // packet is merely used to co-ordinate state transitions 44012027Sjungma@eit.uni-kl.de Packet *snoop_pkt = new Packet(pkt, true, false); 44112027Sjungma@eit.uni-kl.de 44212027Sjungma@eit.uni-kl.de // also reset the bus time that the original packet has 44312027Sjungma@eit.uni-kl.de // not yet paid for 44412027Sjungma@eit.uni-kl.de snoop_pkt->headerDelay = snoop_pkt->payloadDelay = 0; 44512027Sjungma@eit.uni-kl.de 44612027Sjungma@eit.uni-kl.de // make this an instantaneous express snoop, and let the 44712027Sjungma@eit.uni-kl.de // other caches in the system know that the another cache 44812027Sjungma@eit.uni-kl.de // is responding, because we have found the authorative 44912027Sjungma@eit.uni-kl.de // copy (Modified or Owned) that will supply the right 45012027Sjungma@eit.uni-kl.de // data 45112027Sjungma@eit.uni-kl.de snoop_pkt->setExpressSnoop(); 45212027Sjungma@eit.uni-kl.de snoop_pkt->setCacheResponding(); 45312027Sjungma@eit.uni-kl.de 45412027Sjungma@eit.uni-kl.de // this express snoop travels towards the memory, and at 45512027Sjungma@eit.uni-kl.de // every crossbar it is snooped upwards thus reaching 45612027Sjungma@eit.uni-kl.de // every cache in the system 45712027Sjungma@eit.uni-kl.de bool M5_VAR_USED success = memSidePort.sendTimingReq(snoop_pkt); 45812027Sjungma@eit.uni-kl.de // express snoops always succeed 45912027Sjungma@eit.uni-kl.de assert(success); 46012027Sjungma@eit.uni-kl.de 46112027Sjungma@eit.uni-kl.de // main memory will delete the snoop packet 46212027Sjungma@eit.uni-kl.de 46312027Sjungma@eit.uni-kl.de // queue for deletion, as opposed to immediate deletion, as 46412027Sjungma@eit.uni-kl.de // the sending cache is still relying on the packet 46512027Sjungma@eit.uni-kl.de pendingDelete.reset(pkt); 46612027Sjungma@eit.uni-kl.de 46712027Sjungma@eit.uni-kl.de // no need to take any further action in this particular cache 46812027Sjungma@eit.uni-kl.de // as an upstram cache has already committed to responding, 46912027Sjungma@eit.uni-kl.de // and we have already sent out any express snoops in the 47012027Sjungma@eit.uni-kl.de // section above to ensure all other copies in the system are 47112027Sjungma@eit.uni-kl.de // invalidated 47212027Sjungma@eit.uni-kl.de return; 47312027Sjungma@eit.uni-kl.de } 47412027Sjungma@eit.uni-kl.de 47512027Sjungma@eit.uni-kl.de BaseCache::recvTimingReq(pkt); 47612027Sjungma@eit.uni-kl.de} 47712027Sjungma@eit.uni-kl.de 47812027Sjungma@eit.uni-kl.dePacketPtr 47912027Sjungma@eit.uni-kl.deCache::createMissPacket(PacketPtr cpu_pkt, CacheBlk *blk, 48012027Sjungma@eit.uni-kl.de bool needsWritable, 48112027Sjungma@eit.uni-kl.de bool is_whole_line_write) const 48212027Sjungma@eit.uni-kl.de{ 48312027Sjungma@eit.uni-kl.de // should never see evictions here 48412027Sjungma@eit.uni-kl.de assert(!cpu_pkt->isEviction()); 48512027Sjungma@eit.uni-kl.de 48612027Sjungma@eit.uni-kl.de bool blkValid = blk && blk->isValid(); 48712027Sjungma@eit.uni-kl.de 48812027Sjungma@eit.uni-kl.de if (cpu_pkt->req->isUncacheable() || 48912027Sjungma@eit.uni-kl.de (!blkValid && cpu_pkt->isUpgrade()) || 49012027Sjungma@eit.uni-kl.de cpu_pkt->cmd == MemCmd::InvalidateReq || cpu_pkt->isClean()) { 49112027Sjungma@eit.uni-kl.de // uncacheable requests and upgrades from upper-level caches 49212027Sjungma@eit.uni-kl.de // that missed completely just go through as is 49312027Sjungma@eit.uni-kl.de return nullptr; 49412027Sjungma@eit.uni-kl.de } 49512027Sjungma@eit.uni-kl.de 49612027Sjungma@eit.uni-kl.de assert(cpu_pkt->needsResponse()); 49712027Sjungma@eit.uni-kl.de 49812027Sjungma@eit.uni-kl.de MemCmd cmd; 49912027Sjungma@eit.uni-kl.de // @TODO make useUpgrades a parameter. 50012027Sjungma@eit.uni-kl.de // Note that ownership protocols require upgrade, otherwise a 50112027Sjungma@eit.uni-kl.de // write miss on a shared owned block will generate a ReadExcl, 50212027Sjungma@eit.uni-kl.de // which will clobber the owned copy. 50312027Sjungma@eit.uni-kl.de const bool useUpgrades = true; 50412027Sjungma@eit.uni-kl.de assert(cpu_pkt->cmd != MemCmd::WriteLineReq || is_whole_line_write); 50512027Sjungma@eit.uni-kl.de if (is_whole_line_write) { 50612027Sjungma@eit.uni-kl.de assert(!blkValid || !blk->isWritable()); 50712027Sjungma@eit.uni-kl.de // forward as invalidate to all other caches, this gives us 50812027Sjungma@eit.uni-kl.de // the line in Exclusive state, and invalidates all other 50912027Sjungma@eit.uni-kl.de // copies 51012027Sjungma@eit.uni-kl.de cmd = MemCmd::InvalidateReq; 51112027Sjungma@eit.uni-kl.de } else if (blkValid && useUpgrades) { 51212027Sjungma@eit.uni-kl.de // only reason to be here is that blk is read only and we need 51312027Sjungma@eit.uni-kl.de // it to be writable 51412027Sjungma@eit.uni-kl.de assert(needsWritable); 51512027Sjungma@eit.uni-kl.de assert(!blk->isWritable()); 51612027Sjungma@eit.uni-kl.de cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq; 51712027Sjungma@eit.uni-kl.de } else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq || 51812027Sjungma@eit.uni-kl.de cpu_pkt->cmd == MemCmd::StoreCondFailReq) { 51912027Sjungma@eit.uni-kl.de // Even though this SC will fail, we still need to send out the 52012027Sjungma@eit.uni-kl.de // request and get the data to supply it to other snoopers in the case 52112027Sjungma@eit.uni-kl.de // where the determination the StoreCond fails is delayed due to 52212027Sjungma@eit.uni-kl.de // all caches not being on the same local bus. 52312027Sjungma@eit.uni-kl.de cmd = MemCmd::SCUpgradeFailReq; 52412027Sjungma@eit.uni-kl.de } else { 52512027Sjungma@eit.uni-kl.de // block is invalid 52612027Sjungma@eit.uni-kl.de 52712027Sjungma@eit.uni-kl.de // If the request does not need a writable there are two cases 52812027Sjungma@eit.uni-kl.de // where we need to ensure the response will not fetch the 52912027Sjungma@eit.uni-kl.de // block in dirty state: 53012027Sjungma@eit.uni-kl.de // * this cache is read only and it does not perform 53112027Sjungma@eit.uni-kl.de // writebacks, 53212027Sjungma@eit.uni-kl.de // * this cache is mostly exclusive and will not fill (since 53312027Sjungma@eit.uni-kl.de // it does not fill it will have to writeback the dirty data 53412027Sjungma@eit.uni-kl.de // immediately which generates uneccesary writebacks). 53512027Sjungma@eit.uni-kl.de bool force_clean_rsp = isReadOnly || clusivity == Enums::mostly_excl; 53612027Sjungma@eit.uni-kl.de cmd = needsWritable ? MemCmd::ReadExReq : 53712027Sjungma@eit.uni-kl.de (force_clean_rsp ? MemCmd::ReadCleanReq : MemCmd::ReadSharedReq); 53812027Sjungma@eit.uni-kl.de } 53912027Sjungma@eit.uni-kl.de PacketPtr pkt = new Packet(cpu_pkt->req, cmd, blkSize); 54012027Sjungma@eit.uni-kl.de 54112027Sjungma@eit.uni-kl.de // if there are upstream caches that have already marked the 54212027Sjungma@eit.uni-kl.de // packet as having sharers (not passing writable), pass that info 54312027Sjungma@eit.uni-kl.de // downstream 54412027Sjungma@eit.uni-kl.de if (cpu_pkt->hasSharers() && !needsWritable) { 54512027Sjungma@eit.uni-kl.de // note that cpu_pkt may have spent a considerable time in the 54612027Sjungma@eit.uni-kl.de // MSHR queue and that the information could possibly be out 54712027Sjungma@eit.uni-kl.de // of date, however, there is no harm in conservatively 54812027Sjungma@eit.uni-kl.de // assuming the block has sharers 54912027Sjungma@eit.uni-kl.de pkt->setHasSharers(); 55012027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: passing hasSharers from %s to %s\n", 55112027Sjungma@eit.uni-kl.de __func__, cpu_pkt->print(), pkt->print()); 55212027Sjungma@eit.uni-kl.de } 55312027Sjungma@eit.uni-kl.de 55412027Sjungma@eit.uni-kl.de // the packet should be block aligned 55512027Sjungma@eit.uni-kl.de assert(pkt->getAddr() == pkt->getBlockAddr(blkSize)); 55612027Sjungma@eit.uni-kl.de 55712027Sjungma@eit.uni-kl.de pkt->allocate(); 55812027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: created %s from %s\n", __func__, pkt->print(), 55912027Sjungma@eit.uni-kl.de cpu_pkt->print()); 56012027Sjungma@eit.uni-kl.de return pkt; 56112027Sjungma@eit.uni-kl.de} 56212027Sjungma@eit.uni-kl.de 56312027Sjungma@eit.uni-kl.de 56412027Sjungma@eit.uni-kl.deCycles 56512027Sjungma@eit.uni-kl.deCache::handleAtomicReqMiss(PacketPtr pkt, CacheBlk *&blk, 56612027Sjungma@eit.uni-kl.de PacketList &writebacks) 56712027Sjungma@eit.uni-kl.de{ 56812027Sjungma@eit.uni-kl.de // deal with the packets that go through the write path of 56912027Sjungma@eit.uni-kl.de // the cache, i.e. any evictions and writes 57012027Sjungma@eit.uni-kl.de if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean || 57112027Sjungma@eit.uni-kl.de (pkt->req->isUncacheable() && pkt->isWrite())) { 57212027Sjungma@eit.uni-kl.de Cycles latency = ticksToCycles(memSidePort.sendAtomic(pkt)); 57312027Sjungma@eit.uni-kl.de 57412027Sjungma@eit.uni-kl.de // at this point, if the request was an uncacheable write 57512027Sjungma@eit.uni-kl.de // request, it has been satisfied by a memory below and the 57612027Sjungma@eit.uni-kl.de // packet carries the response back 57712027Sjungma@eit.uni-kl.de assert(!(pkt->req->isUncacheable() && pkt->isWrite()) || 57812027Sjungma@eit.uni-kl.de pkt->isResponse()); 57912027Sjungma@eit.uni-kl.de 58012027Sjungma@eit.uni-kl.de return latency; 58112027Sjungma@eit.uni-kl.de } 58212027Sjungma@eit.uni-kl.de 58312027Sjungma@eit.uni-kl.de // only misses left 58412027Sjungma@eit.uni-kl.de 58512027Sjungma@eit.uni-kl.de PacketPtr bus_pkt = createMissPacket(pkt, blk, pkt->needsWritable(), 58612027Sjungma@eit.uni-kl.de pkt->isWholeLineWrite(blkSize)); 58712027Sjungma@eit.uni-kl.de 58812027Sjungma@eit.uni-kl.de bool is_forward = (bus_pkt == nullptr); 58912027Sjungma@eit.uni-kl.de 59012027Sjungma@eit.uni-kl.de if (is_forward) { 59112027Sjungma@eit.uni-kl.de // just forwarding the same request to the next level 59212027Sjungma@eit.uni-kl.de // no local cache operation involved 59312027Sjungma@eit.uni-kl.de bus_pkt = pkt; 59412027Sjungma@eit.uni-kl.de } 59512027Sjungma@eit.uni-kl.de 59612027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: Sending an atomic %s\n", __func__, 59712027Sjungma@eit.uni-kl.de bus_pkt->print()); 59812027Sjungma@eit.uni-kl.de 59912027Sjungma@eit.uni-kl.de#if TRACING_ON 60012027Sjungma@eit.uni-kl.de CacheBlk::State old_state = blk ? blk->status : 0; 60112027Sjungma@eit.uni-kl.de#endif 60212027Sjungma@eit.uni-kl.de 60312027Sjungma@eit.uni-kl.de Cycles latency = ticksToCycles(memSidePort.sendAtomic(bus_pkt)); 60412027Sjungma@eit.uni-kl.de 60512027Sjungma@eit.uni-kl.de bool is_invalidate = bus_pkt->isInvalidate(); 60612027Sjungma@eit.uni-kl.de 60712027Sjungma@eit.uni-kl.de // We are now dealing with the response handling 60812027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: Receive response: %s in state %i\n", __func__, 60912027Sjungma@eit.uni-kl.de bus_pkt->print(), old_state); 61012027Sjungma@eit.uni-kl.de 61112027Sjungma@eit.uni-kl.de // If packet was a forward, the response (if any) is already 61212027Sjungma@eit.uni-kl.de // in place in the bus_pkt == pkt structure, so we don't need 61312027Sjungma@eit.uni-kl.de // to do anything. Otherwise, use the separate bus_pkt to 61412027Sjungma@eit.uni-kl.de // generate response to pkt and then delete it. 61512027Sjungma@eit.uni-kl.de if (!is_forward) { 61612027Sjungma@eit.uni-kl.de if (pkt->needsResponse()) { 61712027Sjungma@eit.uni-kl.de assert(bus_pkt->isResponse()); 61812027Sjungma@eit.uni-kl.de if (bus_pkt->isError()) { 61912027Sjungma@eit.uni-kl.de pkt->makeAtomicResponse(); 62012027Sjungma@eit.uni-kl.de pkt->copyError(bus_pkt); 62112027Sjungma@eit.uni-kl.de } else if (pkt->isWholeLineWrite(blkSize)) { 62212027Sjungma@eit.uni-kl.de // note the use of pkt, not bus_pkt here. 62312027Sjungma@eit.uni-kl.de 62412027Sjungma@eit.uni-kl.de // write-line request to the cache that promoted 62512027Sjungma@eit.uni-kl.de // the write to a whole line 62612027Sjungma@eit.uni-kl.de const bool allocate = allocOnFill(pkt->cmd) && 62712027Sjungma@eit.uni-kl.de (!writeAllocator || writeAllocator->allocate()); 62812027Sjungma@eit.uni-kl.de blk = handleFill(bus_pkt, blk, writebacks, allocate); 62912027Sjungma@eit.uni-kl.de assert(blk != NULL); 63012027Sjungma@eit.uni-kl.de is_invalidate = false; 63112027Sjungma@eit.uni-kl.de satisfyRequest(pkt, blk); 63212027Sjungma@eit.uni-kl.de } else if (bus_pkt->isRead() || 63312027Sjungma@eit.uni-kl.de bus_pkt->cmd == MemCmd::UpgradeResp) { 63412027Sjungma@eit.uni-kl.de // we're updating cache state to allow us to 63512027Sjungma@eit.uni-kl.de // satisfy the upstream request from the cache 63612027Sjungma@eit.uni-kl.de blk = handleFill(bus_pkt, blk, writebacks, 63712027Sjungma@eit.uni-kl.de allocOnFill(pkt->cmd)); 63812027Sjungma@eit.uni-kl.de satisfyRequest(pkt, blk); 63912027Sjungma@eit.uni-kl.de maintainClusivity(pkt->fromCache(), blk); 64012027Sjungma@eit.uni-kl.de } else { 64112027Sjungma@eit.uni-kl.de // we're satisfying the upstream request without 64212027Sjungma@eit.uni-kl.de // modifying cache state, e.g., a write-through 64312027Sjungma@eit.uni-kl.de pkt->makeAtomicResponse(); 64412027Sjungma@eit.uni-kl.de } 64512027Sjungma@eit.uni-kl.de } 64612027Sjungma@eit.uni-kl.de delete bus_pkt; 64712027Sjungma@eit.uni-kl.de } 64812027Sjungma@eit.uni-kl.de 64912027Sjungma@eit.uni-kl.de if (is_invalidate && blk && blk->isValid()) { 65012027Sjungma@eit.uni-kl.de invalidateBlock(blk); 65112027Sjungma@eit.uni-kl.de } 65212027Sjungma@eit.uni-kl.de 65312027Sjungma@eit.uni-kl.de return latency; 65412027Sjungma@eit.uni-kl.de} 65512027Sjungma@eit.uni-kl.de 65612027Sjungma@eit.uni-kl.deTick 65712027Sjungma@eit.uni-kl.deCache::recvAtomic(PacketPtr pkt) 65812027Sjungma@eit.uni-kl.de{ 65912027Sjungma@eit.uni-kl.de promoteWholeLineWrites(pkt); 66012027Sjungma@eit.uni-kl.de 66112027Sjungma@eit.uni-kl.de // follow the same flow as in recvTimingReq, and check if a cache 66212027Sjungma@eit.uni-kl.de // above us is responding 66312027Sjungma@eit.uni-kl.de if (pkt->cacheResponding()) { 66412027Sjungma@eit.uni-kl.de assert(!pkt->req->isCacheInvalidate()); 66512027Sjungma@eit.uni-kl.de DPRINTF(Cache, "Cache above responding to %s: not responding\n", 66612027Sjungma@eit.uni-kl.de pkt->print()); 66712027Sjungma@eit.uni-kl.de 66812027Sjungma@eit.uni-kl.de // if a cache is responding, and it had the line in Owned 66912027Sjungma@eit.uni-kl.de // rather than Modified state, we need to invalidate any 67012027Sjungma@eit.uni-kl.de // copies that are not on the same path to memory 67112027Sjungma@eit.uni-kl.de assert(pkt->needsWritable() && !pkt->responderHadWritable()); 67212027Sjungma@eit.uni-kl.de 67312027Sjungma@eit.uni-kl.de return memSidePort.sendAtomic(pkt); 67412027Sjungma@eit.uni-kl.de } 67512027Sjungma@eit.uni-kl.de 67612027Sjungma@eit.uni-kl.de return BaseCache::recvAtomic(pkt); 67712027Sjungma@eit.uni-kl.de} 67812027Sjungma@eit.uni-kl.de 67912027Sjungma@eit.uni-kl.de 68012027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 68112027Sjungma@eit.uni-kl.de// 68212027Sjungma@eit.uni-kl.de// Response handling: responses from the memory side 68312027Sjungma@eit.uni-kl.de// 68412027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 68512027Sjungma@eit.uni-kl.de 68612027Sjungma@eit.uni-kl.de 68712027Sjungma@eit.uni-kl.devoid 68812027Sjungma@eit.uni-kl.deCache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk) 68912027Sjungma@eit.uni-kl.de{ 69012027Sjungma@eit.uni-kl.de QueueEntry::Target *initial_tgt = mshr->getTarget(); 69112027Sjungma@eit.uni-kl.de // First offset for critical word first calculations 69212027Sjungma@eit.uni-kl.de const int initial_offset = initial_tgt->pkt->getOffset(blkSize); 69312027Sjungma@eit.uni-kl.de 69412027Sjungma@eit.uni-kl.de const bool is_error = pkt->isError(); 69512027Sjungma@eit.uni-kl.de // allow invalidation responses originating from write-line 69612027Sjungma@eit.uni-kl.de // requests to be discarded 69712027Sjungma@eit.uni-kl.de bool is_invalidate = pkt->isInvalidate() && 69812027Sjungma@eit.uni-kl.de !mshr->wasWholeLineWrite; 69912027Sjungma@eit.uni-kl.de 70012027Sjungma@eit.uni-kl.de MSHR::TargetList targets = mshr->extractServiceableTargets(pkt); 70112027Sjungma@eit.uni-kl.de for (auto &target: targets) { 70212027Sjungma@eit.uni-kl.de Packet *tgt_pkt = target.pkt; 70312027Sjungma@eit.uni-kl.de switch (target.source) { 70412027Sjungma@eit.uni-kl.de case MSHR::Target::FromCPU: 70512027Sjungma@eit.uni-kl.de Tick completion_time; 70612027Sjungma@eit.uni-kl.de // Here we charge on completion_time the delay of the xbar if the 70712027Sjungma@eit.uni-kl.de // packet comes from it, charged on headerDelay. 70812027Sjungma@eit.uni-kl.de completion_time = pkt->headerDelay; 70912027Sjungma@eit.uni-kl.de 71012027Sjungma@eit.uni-kl.de // Software prefetch handling for cache closest to core 71112027Sjungma@eit.uni-kl.de if (tgt_pkt->cmd.isSWPrefetch()) { 71212027Sjungma@eit.uni-kl.de // a software prefetch would have already been ack'd 71312027Sjungma@eit.uni-kl.de // immediately with dummy data so the core would be able to 71412027Sjungma@eit.uni-kl.de // retire it. This request completes right here, so we 71512027Sjungma@eit.uni-kl.de // deallocate it. 71612027Sjungma@eit.uni-kl.de delete tgt_pkt; 71712027Sjungma@eit.uni-kl.de break; // skip response 71812027Sjungma@eit.uni-kl.de } 71912027Sjungma@eit.uni-kl.de 72012027Sjungma@eit.uni-kl.de // unlike the other packet flows, where data is found in other 72112027Sjungma@eit.uni-kl.de // caches or memory and brought back, write-line requests always 72212027Sjungma@eit.uni-kl.de // have the data right away, so the above check for "is fill?" 72312027Sjungma@eit.uni-kl.de // cannot actually be determined until examining the stored MSHR 72412027Sjungma@eit.uni-kl.de // state. We "catch up" with that logic here, which is duplicated 72512027Sjungma@eit.uni-kl.de // from above. 72612027Sjungma@eit.uni-kl.de if (tgt_pkt->cmd == MemCmd::WriteLineReq) { 72712027Sjungma@eit.uni-kl.de assert(!is_error); 72812027Sjungma@eit.uni-kl.de assert(blk); 72912027Sjungma@eit.uni-kl.de assert(blk->isWritable()); 73012027Sjungma@eit.uni-kl.de } 73112027Sjungma@eit.uni-kl.de 73212027Sjungma@eit.uni-kl.de if (blk && blk->isValid() && !mshr->isForward) { 73312027Sjungma@eit.uni-kl.de satisfyRequest(tgt_pkt, blk, true, mshr->hasPostDowngrade()); 73412027Sjungma@eit.uni-kl.de 73512027Sjungma@eit.uni-kl.de // How many bytes past the first request is this one 73612027Sjungma@eit.uni-kl.de int transfer_offset = 73712027Sjungma@eit.uni-kl.de tgt_pkt->getOffset(blkSize) - initial_offset; 73812027Sjungma@eit.uni-kl.de if (transfer_offset < 0) { 73912027Sjungma@eit.uni-kl.de transfer_offset += blkSize; 74012027Sjungma@eit.uni-kl.de } 74112027Sjungma@eit.uni-kl.de 74212027Sjungma@eit.uni-kl.de // If not critical word (offset) return payloadDelay. 74312027Sjungma@eit.uni-kl.de // responseLatency is the latency of the return path 74412027Sjungma@eit.uni-kl.de // from lower level caches/memory to an upper level cache or 74512027Sjungma@eit.uni-kl.de // the core. 74612027Sjungma@eit.uni-kl.de completion_time += clockEdge(responseLatency) + 74712027Sjungma@eit.uni-kl.de (transfer_offset ? pkt->payloadDelay : 0); 74812027Sjungma@eit.uni-kl.de 74912027Sjungma@eit.uni-kl.de assert(!tgt_pkt->req->isUncacheable()); 75012027Sjungma@eit.uni-kl.de 75112027Sjungma@eit.uni-kl.de assert(tgt_pkt->req->masterId() < system->maxMasters()); 75212027Sjungma@eit.uni-kl.de missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] += 75312027Sjungma@eit.uni-kl.de completion_time - target.recvTime; 75412027Sjungma@eit.uni-kl.de } else if (pkt->cmd == MemCmd::UpgradeFailResp) { 75512027Sjungma@eit.uni-kl.de // failed StoreCond upgrade 75612027Sjungma@eit.uni-kl.de assert(tgt_pkt->cmd == MemCmd::StoreCondReq || 75712027Sjungma@eit.uni-kl.de tgt_pkt->cmd == MemCmd::StoreCondFailReq || 75812027Sjungma@eit.uni-kl.de tgt_pkt->cmd == MemCmd::SCUpgradeFailReq); 75912027Sjungma@eit.uni-kl.de // responseLatency is the latency of the return path 76012027Sjungma@eit.uni-kl.de // from lower level caches/memory to an upper level cache or 76112027Sjungma@eit.uni-kl.de // the core. 76212027Sjungma@eit.uni-kl.de completion_time += clockEdge(responseLatency) + 76312027Sjungma@eit.uni-kl.de pkt->payloadDelay; 76412027Sjungma@eit.uni-kl.de tgt_pkt->req->setExtraData(0); 76512027Sjungma@eit.uni-kl.de } else { 76612027Sjungma@eit.uni-kl.de // We are about to send a response to a cache above 76712027Sjungma@eit.uni-kl.de // that asked for an invalidation; we need to 76812027Sjungma@eit.uni-kl.de // invalidate our copy immediately as the most 76912027Sjungma@eit.uni-kl.de // up-to-date copy of the block will now be in the 77012027Sjungma@eit.uni-kl.de // cache above. It will also prevent this cache from 77112027Sjungma@eit.uni-kl.de // responding (if the block was previously dirty) to 77212027Sjungma@eit.uni-kl.de // snoops as they should snoop the caches above where 77312027Sjungma@eit.uni-kl.de // they will get the response from. 77412027Sjungma@eit.uni-kl.de if (is_invalidate && blk && blk->isValid()) { 77512027Sjungma@eit.uni-kl.de invalidateBlock(blk); 77612027Sjungma@eit.uni-kl.de } 77712027Sjungma@eit.uni-kl.de // not a cache fill, just forwarding response 77812027Sjungma@eit.uni-kl.de // responseLatency is the latency of the return path 77912027Sjungma@eit.uni-kl.de // from lower level cahces/memory to the core. 78012027Sjungma@eit.uni-kl.de completion_time += clockEdge(responseLatency) + 78112027Sjungma@eit.uni-kl.de pkt->payloadDelay; 78212027Sjungma@eit.uni-kl.de if (pkt->isRead() && !is_error) { 78312027Sjungma@eit.uni-kl.de // sanity check 78412027Sjungma@eit.uni-kl.de assert(pkt->matchAddr(tgt_pkt)); 78512027Sjungma@eit.uni-kl.de assert(pkt->getSize() >= tgt_pkt->getSize()); 78612027Sjungma@eit.uni-kl.de 78712027Sjungma@eit.uni-kl.de tgt_pkt->setData(pkt->getConstPtr<uint8_t>()); 78812027Sjungma@eit.uni-kl.de } 78912027Sjungma@eit.uni-kl.de 79012027Sjungma@eit.uni-kl.de // this response did not allocate here and therefore 79112027Sjungma@eit.uni-kl.de // it was not consumed, make sure that any flags are 79212027Sjungma@eit.uni-kl.de // carried over to cache above 79312027Sjungma@eit.uni-kl.de tgt_pkt->copyResponderFlags(pkt); 79412027Sjungma@eit.uni-kl.de } 79512027Sjungma@eit.uni-kl.de tgt_pkt->makeTimingResponse(); 79612027Sjungma@eit.uni-kl.de // if this packet is an error copy that to the new packet 79712027Sjungma@eit.uni-kl.de if (is_error) 79812027Sjungma@eit.uni-kl.de tgt_pkt->copyError(pkt); 79912027Sjungma@eit.uni-kl.de if (tgt_pkt->cmd == MemCmd::ReadResp && 80012027Sjungma@eit.uni-kl.de (is_invalidate || mshr->hasPostInvalidate())) { 80112027Sjungma@eit.uni-kl.de // If intermediate cache got ReadRespWithInvalidate, 80212027Sjungma@eit.uni-kl.de // propagate that. Response should not have 80312027Sjungma@eit.uni-kl.de // isInvalidate() set otherwise. 80412027Sjungma@eit.uni-kl.de tgt_pkt->cmd = MemCmd::ReadRespWithInvalidate; 80512027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: updated cmd to %s\n", __func__, 80612027Sjungma@eit.uni-kl.de tgt_pkt->print()); 80712027Sjungma@eit.uni-kl.de } 80812027Sjungma@eit.uni-kl.de // Reset the bus additional time as it is now accounted for 80912027Sjungma@eit.uni-kl.de tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0; 81012027Sjungma@eit.uni-kl.de cpuSidePort.schedTimingResp(tgt_pkt, completion_time); 81112027Sjungma@eit.uni-kl.de break; 81212027Sjungma@eit.uni-kl.de 81312027Sjungma@eit.uni-kl.de case MSHR::Target::FromPrefetcher: 81412027Sjungma@eit.uni-kl.de assert(tgt_pkt->cmd == MemCmd::HardPFReq); 81512027Sjungma@eit.uni-kl.de if (blk) 81612027Sjungma@eit.uni-kl.de blk->status |= BlkHWPrefetched; 81712027Sjungma@eit.uni-kl.de delete tgt_pkt; 81812027Sjungma@eit.uni-kl.de break; 81912027Sjungma@eit.uni-kl.de 82012027Sjungma@eit.uni-kl.de case MSHR::Target::FromSnoop: 82112027Sjungma@eit.uni-kl.de // I don't believe that a snoop can be in an error state 82212027Sjungma@eit.uni-kl.de assert(!is_error); 82312027Sjungma@eit.uni-kl.de // response to snoop request 82412027Sjungma@eit.uni-kl.de DPRINTF(Cache, "processing deferred snoop...\n"); 82512027Sjungma@eit.uni-kl.de // If the response is invalidating, a snooping target can 82612027Sjungma@eit.uni-kl.de // be satisfied if it is also invalidating. If the reponse is, not 82712027Sjungma@eit.uni-kl.de // only invalidating, but more specifically an InvalidateResp and 82812027Sjungma@eit.uni-kl.de // the MSHR was created due to an InvalidateReq then a cache above 82912027Sjungma@eit.uni-kl.de // is waiting to satisfy a WriteLineReq. In this case even an 83012027Sjungma@eit.uni-kl.de // non-invalidating snoop is added as a target here since this is 83112027Sjungma@eit.uni-kl.de // the ordering point. When the InvalidateResp reaches this cache, 83212027Sjungma@eit.uni-kl.de // the snooping target will snoop further the cache above with the 83312027Sjungma@eit.uni-kl.de // WriteLineReq. 83412027Sjungma@eit.uni-kl.de assert(!is_invalidate || pkt->cmd == MemCmd::InvalidateResp || 83512027Sjungma@eit.uni-kl.de pkt->req->isCacheMaintenance() || 83612027Sjungma@eit.uni-kl.de mshr->hasPostInvalidate()); 83712027Sjungma@eit.uni-kl.de handleSnoop(tgt_pkt, blk, true, true, mshr->hasPostInvalidate()); 83812027Sjungma@eit.uni-kl.de break; 83912027Sjungma@eit.uni-kl.de 84012027Sjungma@eit.uni-kl.de default: 84112027Sjungma@eit.uni-kl.de panic("Illegal target->source enum %d\n", target.source); 84212027Sjungma@eit.uni-kl.de } 84312027Sjungma@eit.uni-kl.de } 84412027Sjungma@eit.uni-kl.de 84512027Sjungma@eit.uni-kl.de maintainClusivity(targets.hasFromCache, blk); 84612027Sjungma@eit.uni-kl.de 84712027Sjungma@eit.uni-kl.de if (blk && blk->isValid()) { 84812027Sjungma@eit.uni-kl.de // an invalidate response stemming from a write line request 84912027Sjungma@eit.uni-kl.de // should not invalidate the block, so check if the 85012027Sjungma@eit.uni-kl.de // invalidation should be discarded 85112027Sjungma@eit.uni-kl.de if (is_invalidate || mshr->hasPostInvalidate()) { 85212027Sjungma@eit.uni-kl.de invalidateBlock(blk); 85312027Sjungma@eit.uni-kl.de } else if (mshr->hasPostDowngrade()) { 85412027Sjungma@eit.uni-kl.de blk->status &= ~BlkWritable; 85512027Sjungma@eit.uni-kl.de } 85612027Sjungma@eit.uni-kl.de } 85712027Sjungma@eit.uni-kl.de} 85812027Sjungma@eit.uni-kl.de 85912027Sjungma@eit.uni-kl.dePacketPtr 86012027Sjungma@eit.uni-kl.deCache::evictBlock(CacheBlk *blk) 86112027Sjungma@eit.uni-kl.de{ 86212027Sjungma@eit.uni-kl.de PacketPtr pkt = (blk->isDirty() || writebackClean) ? 86312027Sjungma@eit.uni-kl.de writebackBlk(blk) : cleanEvictBlk(blk); 86412027Sjungma@eit.uni-kl.de 86512027Sjungma@eit.uni-kl.de invalidateBlock(blk); 86612027Sjungma@eit.uni-kl.de 86712027Sjungma@eit.uni-kl.de return pkt; 86812027Sjungma@eit.uni-kl.de} 86912027Sjungma@eit.uni-kl.de 87012027Sjungma@eit.uni-kl.dePacketPtr 87112027Sjungma@eit.uni-kl.deCache::cleanEvictBlk(CacheBlk *blk) 87212027Sjungma@eit.uni-kl.de{ 87312027Sjungma@eit.uni-kl.de assert(!writebackClean); 87412027Sjungma@eit.uni-kl.de assert(blk && blk->isValid() && !blk->isDirty()); 87512027Sjungma@eit.uni-kl.de 87612027Sjungma@eit.uni-kl.de // Creating a zero sized write, a message to the snoop filter 87712027Sjungma@eit.uni-kl.de RequestPtr req = std::make_shared<Request>( 87812027Sjungma@eit.uni-kl.de regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId); 87912027Sjungma@eit.uni-kl.de 88012027Sjungma@eit.uni-kl.de if (blk->isSecure()) 88112027Sjungma@eit.uni-kl.de req->setFlags(Request::SECURE); 88212027Sjungma@eit.uni-kl.de 88312027Sjungma@eit.uni-kl.de req->taskId(blk->task_id); 88412027Sjungma@eit.uni-kl.de 88512027Sjungma@eit.uni-kl.de PacketPtr pkt = new Packet(req, MemCmd::CleanEvict); 88612027Sjungma@eit.uni-kl.de pkt->allocate(); 88712027Sjungma@eit.uni-kl.de DPRINTF(Cache, "Create CleanEvict %s\n", pkt->print()); 88812027Sjungma@eit.uni-kl.de 88912027Sjungma@eit.uni-kl.de return pkt; 89012027Sjungma@eit.uni-kl.de} 89112027Sjungma@eit.uni-kl.de 89212027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 89312027Sjungma@eit.uni-kl.de// 89412027Sjungma@eit.uni-kl.de// Snoop path: requests coming in from the memory side 89512027Sjungma@eit.uni-kl.de// 89612027Sjungma@eit.uni-kl.de///////////////////////////////////////////////////// 89712027Sjungma@eit.uni-kl.de 89812027Sjungma@eit.uni-kl.devoid 89912027Sjungma@eit.uni-kl.deCache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data, 90012027Sjungma@eit.uni-kl.de bool already_copied, bool pending_inval) 90112027Sjungma@eit.uni-kl.de{ 90212027Sjungma@eit.uni-kl.de // sanity check 90312027Sjungma@eit.uni-kl.de assert(req_pkt->isRequest()); 90412027Sjungma@eit.uni-kl.de assert(req_pkt->needsResponse()); 90512027Sjungma@eit.uni-kl.de 90612027Sjungma@eit.uni-kl.de DPRINTF(Cache, "%s: for %s\n", __func__, req_pkt->print()); 90712027Sjungma@eit.uni-kl.de // timing-mode snoop responses require a new packet, unless we 90812027Sjungma@eit.uni-kl.de // already made a copy... 90912027Sjungma@eit.uni-kl.de PacketPtr pkt = req_pkt; 91012027Sjungma@eit.uni-kl.de if (!already_copied) 91112027Sjungma@eit.uni-kl.de // do not clear flags, and allocate space for data if the 91212027Sjungma@eit.uni-kl.de // packet needs it (the only packets that carry data are read 91312027Sjungma@eit.uni-kl.de // responses) 91412027Sjungma@eit.uni-kl.de pkt = new Packet(req_pkt, false, req_pkt->isRead()); 91512027Sjungma@eit.uni-kl.de 91612027Sjungma@eit.uni-kl.de assert(req_pkt->req->isUncacheable() || req_pkt->isInvalidate() || 91712027Sjungma@eit.uni-kl.de pkt->hasSharers()); 91812027Sjungma@eit.uni-kl.de pkt->makeTimingResponse(); 91912027Sjungma@eit.uni-kl.de if (pkt->isRead()) { 92012027Sjungma@eit.uni-kl.de pkt->setDataFromBlock(blk_data, blkSize); 92112027Sjungma@eit.uni-kl.de } 92212027Sjungma@eit.uni-kl.de if (pkt->cmd == MemCmd::ReadResp && pending_inval) { 92312027Sjungma@eit.uni-kl.de // Assume we defer a response to a read from a far-away cache 92412027Sjungma@eit.uni-kl.de // A, then later defer a ReadExcl from a cache B on the same 92512027Sjungma@eit.uni-kl.de // bus as us. We'll assert cacheResponding in both cases, but 92612027Sjungma@eit.uni-kl.de // in the latter case cacheResponding will keep the 92712027Sjungma@eit.uni-kl.de // invalidation from reaching cache A. This special response 92812027Sjungma@eit.uni-kl.de // tells cache A that it gets the block to satisfy its read, 92912027Sjungma@eit.uni-kl.de // but must immediately invalidate it. 93012027Sjungma@eit.uni-kl.de pkt->cmd = MemCmd::ReadRespWithInvalidate; 93112027Sjungma@eit.uni-kl.de } 93212027Sjungma@eit.uni-kl.de // Here we consider forward_time, paying for just forward latency and 93312027Sjungma@eit.uni-kl.de // also charging the delay provided by the xbar. 93412027Sjungma@eit.uni-kl.de // forward_time is used as send_time in next allocateWriteBuffer(). 93512027Sjungma@eit.uni-kl.de Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay; 93612027Sjungma@eit.uni-kl.de // Here we reset the timing of the packet. 93712027Sjungma@eit.uni-kl.de pkt->headerDelay = pkt->payloadDelay = 0; 93812027Sjungma@eit.uni-kl.de DPRINTF(CacheVerbose, "%s: created response: %s tick: %lu\n", __func__, 93912027Sjungma@eit.uni-kl.de pkt->print(), forward_time); 94012027Sjungma@eit.uni-kl.de memSidePort.schedTimingSnoopResp(pkt, forward_time); 94112027Sjungma@eit.uni-kl.de} 94212027Sjungma@eit.uni-kl.de 94312027Sjungma@eit.uni-kl.deuint32_t 94412027Sjungma@eit.uni-kl.deCache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, 94512027Sjungma@eit.uni-kl.de bool is_deferred, bool pending_inval) 94612027Sjungma@eit.uni-kl.de{ 94712027Sjungma@eit.uni-kl.de DPRINTF(CacheVerbose, "%s: for %s\n", __func__, pkt->print()); 94812027Sjungma@eit.uni-kl.de // deferred snoops can only happen in timing mode 94912027Sjungma@eit.uni-kl.de assert(!(is_deferred && !is_timing)); 95012027Sjungma@eit.uni-kl.de // pending_inval only makes sense on deferred snoops 95112027Sjungma@eit.uni-kl.de assert(!(pending_inval && !is_deferred)); 95212027Sjungma@eit.uni-kl.de assert(pkt->isRequest()); 95312027Sjungma@eit.uni-kl.de 95412027Sjungma@eit.uni-kl.de // the packet may get modified if we or a forwarded snooper 95512027Sjungma@eit.uni-kl.de // responds in atomic mode, so remember a few things about the 95612027Sjungma@eit.uni-kl.de // original packet up front 95712027Sjungma@eit.uni-kl.de bool invalidate = pkt->isInvalidate(); 95812027Sjungma@eit.uni-kl.de bool M5_VAR_USED needs_writable = pkt->needsWritable(); 95912027Sjungma@eit.uni-kl.de 960 // at the moment we could get an uncacheable write which does not 961 // have the invalidate flag, and we need a suitable way of dealing 962 // with this case 963 panic_if(invalidate && pkt->req->isUncacheable(), 964 "%s got an invalidating uncacheable snoop request %s", 965 name(), pkt->print()); 966 967 uint32_t snoop_delay = 0; 968 969 if (forwardSnoops) { 970 // first propagate snoop upward to see if anyone above us wants to 971 // handle it. save & restore packet src since it will get 972 // rewritten to be relative to cpu-side bus (if any) 973 if (is_timing) { 974 // copy the packet so that we can clear any flags before 975 // forwarding it upwards, we also allocate data (passing 976 // the pointer along in case of static data), in case 977 // there is a snoop hit in upper levels 978 Packet snoopPkt(pkt, true, true); 979 snoopPkt.setExpressSnoop(); 980 // the snoop packet does not need to wait any additional 981 // time 982 snoopPkt.headerDelay = snoopPkt.payloadDelay = 0; 983 cpuSidePort.sendTimingSnoopReq(&snoopPkt); 984 985 // add the header delay (including crossbar and snoop 986 // delays) of the upward snoop to the snoop delay for this 987 // cache 988 snoop_delay += snoopPkt.headerDelay; 989 990 // If this request is a prefetch or clean evict and an upper level 991 // signals block present, make sure to propagate the block 992 // presence to the requester. 993 if (snoopPkt.isBlockCached()) { 994 pkt->setBlockCached(); 995 } 996 // If the request was satisfied by snooping the cache 997 // above, mark the original packet as satisfied too. 998 if (snoopPkt.satisfied()) { 999 pkt->setSatisfied(); 1000 } 1001 1002 // Copy over flags from the snoop response to make sure we 1003 // inform the final destination 1004 pkt->copyResponderFlags(&snoopPkt); 1005 } else { 1006 bool already_responded = pkt->cacheResponding(); 1007 cpuSidePort.sendAtomicSnoop(pkt); 1008 if (!already_responded && pkt->cacheResponding()) { 1009 // cache-to-cache response from some upper cache: 1010 // forward response to original requester 1011 assert(pkt->isResponse()); 1012 } 1013 } 1014 } 1015 1016 bool respond = false; 1017 bool blk_valid = blk && blk->isValid(); 1018 if (pkt->isClean()) { 1019 if (blk_valid && blk->isDirty()) { 1020 DPRINTF(CacheVerbose, "%s: packet (snoop) %s found block: %s\n", 1021 __func__, pkt->print(), blk->print()); 1022 PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id); 1023 PacketList writebacks; 1024 writebacks.push_back(wb_pkt); 1025 1026 if (is_timing) { 1027 // anything that is merely forwarded pays for the forward 1028 // latency and the delay provided by the crossbar 1029 Tick forward_time = clockEdge(forwardLatency) + 1030 pkt->headerDelay; 1031 doWritebacks(writebacks, forward_time); 1032 } else { 1033 doWritebacksAtomic(writebacks); 1034 } 1035 pkt->setSatisfied(); 1036 } 1037 } else if (!blk_valid) { 1038 DPRINTF(CacheVerbose, "%s: snoop miss for %s\n", __func__, 1039 pkt->print()); 1040 if (is_deferred) { 1041 // we no longer have the block, and will not respond, but a 1042 // packet was allocated in MSHR::handleSnoop and we have 1043 // to delete it 1044 assert(pkt->needsResponse()); 1045 1046 // we have passed the block to a cache upstream, that 1047 // cache should be responding 1048 assert(pkt->cacheResponding()); 1049 1050 delete pkt; 1051 } 1052 return snoop_delay; 1053 } else { 1054 DPRINTF(Cache, "%s: snoop hit for %s, old state is %s\n", __func__, 1055 pkt->print(), blk->print()); 1056 1057 // We may end up modifying both the block state and the packet (if 1058 // we respond in atomic mode), so just figure out what to do now 1059 // and then do it later. We respond to all snoops that need 1060 // responses provided we have the block in dirty state. The 1061 // invalidation itself is taken care of below. We don't respond to 1062 // cache maintenance operations as this is done by the destination 1063 // xbar. 1064 respond = blk->isDirty() && pkt->needsResponse(); 1065 1066 chatty_assert(!(isReadOnly && blk->isDirty()), "Should never have " 1067 "a dirty block in a read-only cache %s\n", name()); 1068 } 1069 1070 // Invalidate any prefetch's from below that would strip write permissions 1071 // MemCmd::HardPFReq is only observed by upstream caches. After missing 1072 // above and in it's own cache, a new MemCmd::ReadReq is created that 1073 // downstream caches observe. 1074 if (pkt->mustCheckAbove()) { 1075 DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s " 1076 "from lower cache\n", pkt->getAddr(), pkt->print()); 1077 pkt->setBlockCached(); 1078 return snoop_delay; 1079 } 1080 1081 if (pkt->isRead() && !invalidate) { 1082 // reading without requiring the line in a writable state 1083 assert(!needs_writable); 1084 pkt->setHasSharers(); 1085 1086 // if the requesting packet is uncacheable, retain the line in 1087 // the current state, otherwhise unset the writable flag, 1088 // which means we go from Modified to Owned (and will respond 1089 // below), remain in Owned (and will respond below), from 1090 // Exclusive to Shared, or remain in Shared 1091 if (!pkt->req->isUncacheable()) 1092 blk->status &= ~BlkWritable; 1093 DPRINTF(Cache, "new state is %s\n", blk->print()); 1094 } 1095 1096 if (respond) { 1097 // prevent anyone else from responding, cache as well as 1098 // memory, and also prevent any memory from even seeing the 1099 // request 1100 pkt->setCacheResponding(); 1101 if (!pkt->isClean() && blk->isWritable()) { 1102 // inform the cache hierarchy that this cache had the line 1103 // in the Modified state so that we avoid unnecessary 1104 // invalidations (see Packet::setResponderHadWritable) 1105 pkt->setResponderHadWritable(); 1106 1107 // in the case of an uncacheable request there is no point 1108 // in setting the responderHadWritable flag, but since the 1109 // recipient does not care there is no harm in doing so 1110 } else { 1111 // if the packet has needsWritable set we invalidate our 1112 // copy below and all other copies will be invalidates 1113 // through express snoops, and if needsWritable is not set 1114 // we already called setHasSharers above 1115 } 1116 1117 // if we are returning a writable and dirty (Modified) line, 1118 // we should be invalidating the line 1119 panic_if(!invalidate && !pkt->hasSharers(), 1120 "%s is passing a Modified line through %s, " 1121 "but keeping the block", name(), pkt->print()); 1122 1123 if (is_timing) { 1124 doTimingSupplyResponse(pkt, blk->data, is_deferred, pending_inval); 1125 } else { 1126 pkt->makeAtomicResponse(); 1127 // packets such as upgrades do not actually have any data 1128 // payload 1129 if (pkt->hasData()) 1130 pkt->setDataFromBlock(blk->data, blkSize); 1131 } 1132 1133 // When a block is compressed, it must first be decompressed before 1134 // being read, and this increases the snoop delay. 1135 if (compressor && pkt->isRead()) { 1136 snoop_delay += compressor->getDecompressionLatency(blk); 1137 } 1138 } 1139 1140 if (!respond && is_deferred) { 1141 assert(pkt->needsResponse()); 1142 delete pkt; 1143 } 1144 1145 // Do this last in case it deallocates block data or something 1146 // like that 1147 if (blk_valid && invalidate) { 1148 invalidateBlock(blk); 1149 DPRINTF(Cache, "new state is %s\n", blk->print()); 1150 } 1151 1152 return snoop_delay; 1153} 1154 1155 1156void 1157Cache::recvTimingSnoopReq(PacketPtr pkt) 1158{ 1159 DPRINTF(CacheVerbose, "%s: for %s\n", __func__, pkt->print()); 1160 1161 // no need to snoop requests that are not in range 1162 if (!inRange(pkt->getAddr())) { 1163 return; 1164 } 1165 1166 bool is_secure = pkt->isSecure(); 1167 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure); 1168 1169 Addr blk_addr = pkt->getBlockAddr(blkSize); 1170 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure); 1171 1172 // Update the latency cost of the snoop so that the crossbar can 1173 // account for it. Do not overwrite what other neighbouring caches 1174 // have already done, rather take the maximum. The update is 1175 // tentative, for cases where we return before an upward snoop 1176 // happens below. 1177 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, 1178 lookupLatency * clockPeriod()); 1179 1180 // Inform request(Prefetch, CleanEvict or Writeback) from below of 1181 // MSHR hit, set setBlockCached. 1182 if (mshr && pkt->mustCheckAbove()) { 1183 DPRINTF(Cache, "Setting block cached for %s from lower cache on " 1184 "mshr hit\n", pkt->print()); 1185 pkt->setBlockCached(); 1186 return; 1187 } 1188 1189 // Let the MSHR itself track the snoop and decide whether we want 1190 // to go ahead and do the regular cache snoop 1191 if (mshr && mshr->handleSnoop(pkt, order++)) { 1192 DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %#llx (%s)." 1193 "mshrs: %s\n", blk_addr, is_secure ? "s" : "ns", 1194 mshr->print()); 1195 1196 if (mshr->getNumTargets() > numTarget) 1197 warn("allocating bonus target for snoop"); //handle later 1198 return; 1199 } 1200 1201 //We also need to check the writeback buffers and handle those 1202 WriteQueueEntry *wb_entry = writeBuffer.findMatch(blk_addr, is_secure); 1203 if (wb_entry) { 1204 DPRINTF(Cache, "Snoop hit in writeback to addr %#llx (%s)\n", 1205 pkt->getAddr(), is_secure ? "s" : "ns"); 1206 // Expect to see only Writebacks and/or CleanEvicts here, both of 1207 // which should not be generated for uncacheable data. 1208 assert(!wb_entry->isUncacheable()); 1209 // There should only be a single request responsible for generating 1210 // Writebacks/CleanEvicts. 1211 assert(wb_entry->getNumTargets() == 1); 1212 PacketPtr wb_pkt = wb_entry->getTarget()->pkt; 1213 assert(wb_pkt->isEviction() || wb_pkt->cmd == MemCmd::WriteClean); 1214 1215 if (pkt->isEviction()) { 1216 // if the block is found in the write queue, set the BLOCK_CACHED 1217 // flag for Writeback/CleanEvict snoop. On return the snoop will 1218 // propagate the BLOCK_CACHED flag in Writeback packets and prevent 1219 // any CleanEvicts from travelling down the memory hierarchy. 1220 pkt->setBlockCached(); 1221 DPRINTF(Cache, "%s: Squashing %s from lower cache on writequeue " 1222 "hit\n", __func__, pkt->print()); 1223 return; 1224 } 1225 1226 // conceptually writebacks are no different to other blocks in 1227 // this cache, so the behaviour is modelled after handleSnoop, 1228 // the difference being that instead of querying the block 1229 // state to determine if it is dirty and writable, we use the 1230 // command and fields of the writeback packet 1231 bool respond = wb_pkt->cmd == MemCmd::WritebackDirty && 1232 pkt->needsResponse(); 1233 bool have_writable = !wb_pkt->hasSharers(); 1234 bool invalidate = pkt->isInvalidate(); 1235 1236 if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) { 1237 assert(!pkt->needsWritable()); 1238 pkt->setHasSharers(); 1239 wb_pkt->setHasSharers(); 1240 } 1241 1242 if (respond) { 1243 pkt->setCacheResponding(); 1244 1245 if (have_writable) { 1246 pkt->setResponderHadWritable(); 1247 } 1248 1249 doTimingSupplyResponse(pkt, wb_pkt->getConstPtr<uint8_t>(), 1250 false, false); 1251 } 1252 1253 if (invalidate && wb_pkt->cmd != MemCmd::WriteClean) { 1254 // Invalidation trumps our writeback... discard here 1255 // Note: markInService will remove entry from writeback buffer. 1256 markInService(wb_entry); 1257 delete wb_pkt; 1258 } 1259 } 1260 1261 // If this was a shared writeback, there may still be 1262 // other shared copies above that require invalidation. 1263 // We could be more selective and return here if the 1264 // request is non-exclusive or if the writeback is 1265 // exclusive. 1266 uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false); 1267 1268 // Override what we did when we first saw the snoop, as we now 1269 // also have the cost of the upwards snoops to account for 1270 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay + 1271 lookupLatency * clockPeriod()); 1272} 1273 1274Tick 1275Cache::recvAtomicSnoop(PacketPtr pkt) 1276{ 1277 // no need to snoop requests that are not in range. 1278 if (!inRange(pkt->getAddr())) { 1279 return 0; 1280 } 1281 1282 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure()); 1283 uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false); 1284 return snoop_delay + lookupLatency * clockPeriod(); 1285} 1286 1287bool 1288Cache::isCachedAbove(PacketPtr pkt, bool is_timing) 1289{ 1290 if (!forwardSnoops) 1291 return false; 1292 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and 1293 // Writeback snoops into upper level caches to check for copies of the 1294 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict 1295 // packet, the cache can inform the crossbar below of presence or absence 1296 // of the block. 1297 if (is_timing) { 1298 Packet snoop_pkt(pkt, true, false); 1299 snoop_pkt.setExpressSnoop(); 1300 // Assert that packet is either Writeback or CleanEvict and not a 1301 // prefetch request because prefetch requests need an MSHR and may 1302 // generate a snoop response. 1303 assert(pkt->isEviction() || pkt->cmd == MemCmd::WriteClean); 1304 snoop_pkt.senderState = nullptr; 1305 cpuSidePort.sendTimingSnoopReq(&snoop_pkt); 1306 // Writeback/CleanEvict snoops do not generate a snoop response. 1307 assert(!(snoop_pkt.cacheResponding())); 1308 return snoop_pkt.isBlockCached(); 1309 } else { 1310 cpuSidePort.sendAtomicSnoop(pkt); 1311 return pkt->isBlockCached(); 1312 } 1313} 1314 1315bool 1316Cache::sendMSHRQueuePacket(MSHR* mshr) 1317{ 1318 assert(mshr); 1319 1320 // use request from 1st target 1321 PacketPtr tgt_pkt = mshr->getTarget()->pkt; 1322 1323 if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) { 1324 DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print()); 1325 1326 // we should never have hardware prefetches to allocated 1327 // blocks 1328 assert(!tags->findBlock(mshr->blkAddr, mshr->isSecure)); 1329 1330 // We need to check the caches above us to verify that 1331 // they don't have a copy of this block in the dirty state 1332 // at the moment. Without this check we could get a stale 1333 // copy from memory that might get used in place of the 1334 // dirty one. 1335 Packet snoop_pkt(tgt_pkt, true, false); 1336 snoop_pkt.setExpressSnoop(); 1337 // We are sending this packet upwards, but if it hits we will 1338 // get a snoop response that we end up treating just like a 1339 // normal response, hence it needs the MSHR as its sender 1340 // state 1341 snoop_pkt.senderState = mshr; 1342 cpuSidePort.sendTimingSnoopReq(&snoop_pkt); 1343 1344 // Check to see if the prefetch was squashed by an upper cache (to 1345 // prevent us from grabbing the line) or if a Check to see if a 1346 // writeback arrived between the time the prefetch was placed in 1347 // the MSHRs and when it was selected to be sent or if the 1348 // prefetch was squashed by an upper cache. 1349 1350 // It is important to check cacheResponding before 1351 // prefetchSquashed. If another cache has committed to 1352 // responding, it will be sending a dirty response which will 1353 // arrive at the MSHR allocated for this request. Checking the 1354 // prefetchSquash first may result in the MSHR being 1355 // prematurely deallocated. 1356 if (snoop_pkt.cacheResponding()) { 1357 auto M5_VAR_USED r = outstandingSnoop.insert(snoop_pkt.req); 1358 assert(r.second); 1359 1360 // if we are getting a snoop response with no sharers it 1361 // will be allocated as Modified 1362 bool pending_modified_resp = !snoop_pkt.hasSharers(); 1363 markInService(mshr, pending_modified_resp); 1364 1365 DPRINTF(Cache, "Upward snoop of prefetch for addr" 1366 " %#x (%s) hit\n", 1367 tgt_pkt->getAddr(), tgt_pkt->isSecure()? "s": "ns"); 1368 return false; 1369 } 1370 1371 if (snoop_pkt.isBlockCached()) { 1372 DPRINTF(Cache, "Block present, prefetch squashed by cache. " 1373 "Deallocating mshr target %#x.\n", 1374 mshr->blkAddr); 1375 1376 // Deallocate the mshr target 1377 if (mshrQueue.forceDeallocateTarget(mshr)) { 1378 // Clear block if this deallocation resulted freed an 1379 // mshr when all had previously been utilized 1380 clearBlocked(Blocked_NoMSHRs); 1381 } 1382 1383 // given that no response is expected, delete Request and Packet 1384 delete tgt_pkt; 1385 1386 return false; 1387 } 1388 } 1389 1390 return BaseCache::sendMSHRQueuePacket(mshr); 1391} 1392 1393Cache* 1394CacheParams::create() 1395{ 1396 assert(tags); 1397 assert(replacement_policy); 1398 1399 return new Cache(this); 1400} 1401