fa_lru.cc revision 10941:a39646f4c407 
1/*
2 * Copyright (c) 2013 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2003-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Erik Hallnor
41 */
42
43/**
44 * @file
45 * Definitions a fully associative LRU tagstore.
46 */
47
48#include <cassert>
49#include <sstream>
50
51#include "base/intmath.hh"
52#include "base/misc.hh"
53#include "mem/cache/tags/fa_lru.hh"
54
55using namespace std;
56
57FALRU::FALRU(const Params *p)
58    : BaseTags(p), cacheBoundaries(nullptr)
59{
60    if (!isPowerOf2(blkSize))
61        fatal("cache block size (in bytes) `%d' must be a power of two",
62              blkSize);
63    if (!isPowerOf2(size))
64        fatal("Cache Size must be power of 2 for now");
65
66    // Track all cache sizes from 128K up by powers of 2
67    numCaches = floorLog2(size) - 17;
68    if (numCaches >0){
69        cacheBoundaries = new FALRUBlk *[numCaches];
70        cacheMask = (1 << numCaches) - 1;
71    } else {
72        cacheMask = 0;
73    }
74
75    warmupBound = size/blkSize;
76    numBlocks = size/blkSize;
77
78    blks = new FALRUBlk[numBlocks];
79    head = &(blks[0]);
80    tail = &(blks[numBlocks-1]);
81
82    head->prev = NULL;
83    head->next = &(blks[1]);
84    head->inCache = cacheMask;
85
86    tail->prev = &(blks[numBlocks-2]);
87    tail->next = NULL;
88    tail->inCache = 0;
89
90    unsigned index = (1 << 17) / blkSize;
91    unsigned j = 0;
92    int flags = cacheMask;
93    for (unsigned i = 1; i < numBlocks - 1; i++) {
94        blks[i].inCache = flags;
95        if (i == index - 1){
96            cacheBoundaries[j] = &(blks[i]);
97            flags &= ~ (1<<j);
98            ++j;
99            index = index << 1;
100        }
101        blks[i].prev = &(blks[i-1]);
102        blks[i].next = &(blks[i+1]);
103        blks[i].isTouched = false;
104        blks[i].set = 0;
105        blks[i].way = i;
106    }
107    assert(j == numCaches);
108    assert(index == numBlocks);
109    //assert(check());
110}
111
112FALRU::~FALRU()
113{
114    if (numCaches)
115        delete[] cacheBoundaries;
116
117    delete[] blks;
118}
119
120void
121FALRU::regStats()
122{
123    using namespace Stats;
124    BaseTags::regStats();
125    hits
126        .init(numCaches+1)
127        .name(name() + ".falru_hits")
128        .desc("The number of hits in each cache size.")
129        ;
130    misses
131        .init(numCaches+1)
132        .name(name() + ".falru_misses")
133        .desc("The number of misses in each cache size.")
134        ;
135    accesses
136        .name(name() + ".falru_accesses")
137        .desc("The number of accesses to the FA LRU cache.")
138        ;
139
140    for (unsigned i = 0; i <= numCaches; ++i) {
141        stringstream size_str;
142        if (i < 3){
143            size_str << (1<<(i+7)) <<"K";
144        } else {
145            size_str << (1<<(i-3)) <<"M";
146        }
147
148        hits.subname(i, size_str.str());
149        hits.subdesc(i, "Hits in a " + size_str.str() +" cache");
150        misses.subname(i, size_str.str());
151        misses.subdesc(i, "Misses in a " + size_str.str() +" cache");
152    }
153}
154
155FALRUBlk *
156FALRU::hashLookup(Addr addr) const
157{
158    tagIterator iter = tagHash.find(addr);
159    if (iter != tagHash.end()) {
160        return (*iter).second;
161    }
162    return NULL;
163}
164
165void
166FALRU::invalidate(CacheBlk *blk)
167{
168    assert(blk);
169    tagsInUse--;
170}
171
172CacheBlk*
173FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, int context_src)
174{
175    return accessBlock(addr, is_secure, lat, context_src, 0);
176}
177
178CacheBlk*
179FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, int context_src,
180                   int *inCache)
181{
182    accesses++;
183    int tmp_in_cache = 0;
184    Addr blkAddr = blkAlign(addr);
185    FALRUBlk* blk = hashLookup(blkAddr);
186
187    if (blk && blk->isValid()) {
188        assert(blk->tag == blkAddr);
189        tmp_in_cache = blk->inCache;
190        for (unsigned i = 0; i < numCaches; i++) {
191            if (1<<i & blk->inCache) {
192                hits[i]++;
193            } else {
194                misses[i]++;
195            }
196        }
197        hits[numCaches]++;
198        if (blk != head){
199            moveToHead(blk);
200        }
201    } else {
202        blk = NULL;
203        for (unsigned i = 0; i <= numCaches; ++i) {
204            misses[i]++;
205        }
206    }
207    if (inCache) {
208        *inCache = tmp_in_cache;
209    }
210
211    lat = accessLatency;
212    //assert(check());
213    return blk;
214}
215
216
217CacheBlk*
218FALRU::findBlock(Addr addr, bool is_secure) const
219{
220    Addr blkAddr = blkAlign(addr);
221    FALRUBlk* blk = hashLookup(blkAddr);
222
223    if (blk && blk->isValid()) {
224        assert(blk->tag == blkAddr);
225    } else {
226        blk = NULL;
227    }
228    return blk;
229}
230
231CacheBlk*
232FALRU::findBlockBySetAndWay(int set, int way) const
233{
234    assert(set == 0);
235    return &blks[way];
236}
237
238CacheBlk*
239FALRU::findVictim(Addr addr)
240{
241    FALRUBlk * blk = tail;
242    assert(blk->inCache == 0);
243    moveToHead(blk);
244    tagHash.erase(blk->tag);
245    tagHash[blkAlign(addr)] = blk;
246    if (blk->isValid()) {
247        replacements[0]++;
248    } else {
249        tagsInUse++;
250        blk->isTouched = true;
251        if (!warmedUp && tagsInUse.value() >= warmupBound) {
252            warmedUp = true;
253            warmupCycle = curTick();
254        }
255    }
256    //assert(check());
257    return blk;
258}
259
260void
261FALRU::insertBlock(PacketPtr pkt, CacheBlk *blk)
262{
263}
264
265void
266FALRU::moveToHead(FALRUBlk *blk)
267{
268    int updateMask = blk->inCache ^ cacheMask;
269    for (unsigned i = 0; i < numCaches; i++){
270        if ((1<<i) & updateMask) {
271            cacheBoundaries[i]->inCache &= ~(1<<i);
272            cacheBoundaries[i] = cacheBoundaries[i]->prev;
273        } else if (cacheBoundaries[i] == blk) {
274            cacheBoundaries[i] = blk->prev;
275        }
276    }
277    blk->inCache = cacheMask;
278    if (blk != head) {
279        if (blk == tail){
280            assert(blk->next == NULL);
281            tail = blk->prev;
282            tail->next = NULL;
283        } else {
284            blk->prev->next = blk->next;
285            blk->next->prev = blk->prev;
286        }
287        blk->next = head;
288        blk->prev = NULL;
289        head->prev = blk;
290        head = blk;
291    }
292}
293
294bool
295FALRU::check()
296{
297    FALRUBlk* blk = head;
298    int tot_size = 0;
299    int boundary = 1<<17;
300    int j = 0;
301    int flags = cacheMask;
302    while (blk) {
303        tot_size += blkSize;
304        if (blk->inCache != flags) {
305            return false;
306        }
307        if (tot_size == boundary && blk != tail) {
308            if (cacheBoundaries[j] != blk) {
309                return false;
310            }
311            flags &=~(1 << j);
312            boundary = boundary<<1;
313            ++j;
314        }
315        blk = blk->next;
316    }
317    return true;
318}
319
320void
321FALRU::clearLocks()
322{
323    for (int i = 0; i < numBlocks; i++){
324        blks[i].clearLoadLocks();
325    }
326}
327
328FALRU *
329FALRUParams::create()
330{
331    return new FALRU(this);
332}
333
334