src/sim/dvfs_handler.cc

/*
 * Copyright (c) 2013-2014 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
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 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Vasileios Spiliopoulos
 *          Akash Bagdia
 *          Stephan Diestelhorst
 */

#include <set>
#include <utility>

#include "base/misc.hh"
#include "debug/DVFS.hh"
#include "params/DVFSHandler.hh"
#include "sim/clock_domain.hh"
#include "sim/dvfs_handler.hh"
#include "sim/stat_control.hh"
#include "sim/voltage_domain.hh"

//
//
// DVFSHandler methods implementation
//

DVFSHandler::DVFSHandler(const Params *p)
    : SimObject(p),
      sysClkDomain(p->sys_clk_domain),
      enableHandler(p->enable),
      _transLatency(p->transition_latency)
{
    // Check supplied list of domains for sanity and add them to the
    // domain ID -> domain* hash
    for(auto dit = p->domains.begin(); dit != p->domains.end(); ++dit) {
        SrcClockDomain *d = *dit;
        DomainID domain_id = d->domainID();

        fatal_if(sysClkDomain == d, "DVFS: Domain config list has a "\
                 "system clk domain entry");
        fatal_if(domain_id == SrcClockDomain::emptyDomainID,
                 "DVFS: Controlled domain %s needs to have a properly "\
                 " assigned ID.\n", d->name());

        auto entry = std::make_pair(domain_id, d);
        bool new_elem = domains.insert(entry).second;
        fatal_if(!new_elem, "DVFS: Domain %s with ID %d does not have a "\
                 "unique ID.\n", d->name(), domain_id);

        // Create a dedicated event slot per known domain ID
        UpdateEvent *event = &updatePerfLevelEvents[domain_id];
        event->domainIDToSet = d->domainID();
    }
    UpdateEvent::dvfsHandler = this;
}

DVFSHandler *DVFSHandler::UpdateEvent::dvfsHandler;

bool
DVFSHandler::validDomainID(DomainID domain_id) const
{
    assert(isEnabled());
    // This is ensure that the domain id as requested by the software is
    // availabe in the handler.
    if (domains.find(domain_id) != domains.end())
        return true;
    warn("DVFS: invalid domain ID %d, the DVFS handler does not handle this "\
         "domain\n", domain_id);
    return false;
}

bool
DVFSHandler::perfLevel(DomainID domain_id, PerfLevel perf_level)
{
    assert(isEnabled());

    DPRINTF(DVFS, "DVFS: setPerfLevel domain %d -> %d\n", domain_id, perf_level);

    auto d = findDomain(domain_id);
    if (!d->validPerfLevel(perf_level)) {
        warn("DVFS: invalid performance level %d for domain ID %d, request "\
             "ignored\n", perf_level, domain_id);
        return false;
    }

    UpdateEvent *update_event = &updatePerfLevelEvents[domain_id];
    // Drop an old DVFS change request once we have established that this is a
    // reasonable request
    if (update_event->scheduled()) {
        DPRINTF(DVFS, "DVFS: Overwriting the previous DVFS event.\n");
        deschedule(update_event);
    }

    update_event->perfLevelToSet = perf_level;

    // State changes that restore to the current state (and / or overwrite a not
    // yet completed in-flight request) will be squashed
    if (d->perfLevel() == perf_level) {
        DPRINTF(DVFS, "DVFS: Ignoring ineffective performance level change "\
                "%d -> %d\n", d->perfLevel(), perf_level);
        return false;
    }

    // At this point, a new transition will certainly take place -> schedule
    Tick when = curTick() + _transLatency;
    DPRINTF(DVFS, "DVFS: Update for perf event scheduled for %ld\n", when);

    schedule(update_event, when);
    return true;
}

void
DVFSHandler::UpdateEvent::updatePerfLevel()
{
    // Perform explicit stats dump for power estimation before performance
    // level migration
    Stats::dump();
    Stats::reset();

    // Update the performance level in the clock domain
    auto d = dvfsHandler->findDomain(domainIDToSet);
    assert(d->perfLevel() != perfLevelToSet);

    d->perfLevel(perfLevelToSet);
}

void
DVFSHandler::serialize(std::ostream &os)
{
    //This is to ensure that the handler status is maintained during the
    //entire simulation run and not changed from command line during checkpoint
    //and restore
    SERIALIZE_SCALAR(enableHandler);

    // Pull out the hashed data structure into easy-to-serialise arrays;
    // ensuring that the data associated with any pending update event is saved
    std::vector<DomainID> domain_ids;
    std::vector<PerfLevel> perf_levels;
    std::vector<Tick> whens;
    for (auto it = updatePerfLevelEvents.begin();
         it != updatePerfLevelEvents.end(); ++it) {
        DomainID id = it->first;
        UpdateEvent *event = &it->second;

        assert(id == event->domainIDToSet);
        domain_ids.push_back(id);
        perf_levels.push_back(event->perfLevelToSet);
        whens.push_back(event->scheduled() ? event->when() : 0);
    }
    arrayParamOut(os, "domain_ids", domain_ids);
    arrayParamOut(os, "perf_levels", perf_levels);
    arrayParamOut(os, "whens", whens);
}

void
DVFSHandler::unserialize(Checkpoint *cp, const std::string &section)
{
    UNSERIALIZE_SCALAR(enableHandler);

    // Reconstruct the map of domain IDs and their scheduled events
    std::vector<DomainID> domain_ids;
    std::vector<PerfLevel> perf_levels;
    std::vector<Tick> whens;
    arrayParamIn(cp, section, "domain_ids", domain_ids);
    arrayParamIn(cp, section, "perf_levels", perf_levels);
    arrayParamIn(cp, section, "whens", whens);

    for (size_t i = 0; i < domain_ids.size(); ++i) {;
        UpdateEvent *event = &updatePerfLevelEvents[domain_ids[i]];

        event->domainIDToSet = domain_ids[i];
        event->perfLevelToSet = perf_levels[i];

        // Schedule all previously scheduled events
        if (whens[i])
            schedule(event, whens[i]);
    }
    UpdateEvent::dvfsHandler = this;
}

DVFSHandler*
DVFSHandlerParams::create()
{
    return new DVFSHandler(this);
}