stack_dist.cc

Go to the documentation of this file.

/*
 * Copyright (c) 2015 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.
 *
 * Redistribution and use in source and binary forms, with or without
 * 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
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include "mem/probes/stack_dist.hh"
 
#include "params/StackDistProbe.hh"
#include "sim/system.hh"
 
namespace gem5
{
 
StackDistProbe::StackDistProbe(const StackDistProbeParams &p)
    : BaseMemProbe(p),
      lineSize(p.line_size),
      disableLinearHists(p.disable_linear_hists),
      disableLogHists(p.disable_log_hists),
      calc(p.verify),
      stats(this)
{
    fatal_if(p.system->cacheLineSize() > p.line_size,
             "The stack distance probe must use a cache line size that is "
             "larger or equal to the system's cahce line size.");
}
 
StackDistProbe::StackDistProbeStats::StackDistProbeStats(
    StackDistProbe *parent)
    : statistics::Group(parent),
      ADD_STAT(readLinearHist, statistics::units::Count::get(),
               "Reads linear distribution"),
      ADD_STAT(readLogHist, statistics::units::Ratio::get(),
               "Reads logarithmic distribution"),
      ADD_STAT(writeLinearHist, statistics::units::Count::get(),
               "Writes linear distribution"),
      ADD_STAT(writeLogHist, statistics::units::Ratio::get(),
               "Writes logarithmic distribution"),
      ADD_STAT(infiniteSD, statistics::units::Count::get(),
               "Number of requests with infinite stack distance")
{
    using namespace statistics;
 
    const StackDistProbeParams &p =
        dynamic_cast<const StackDistProbeParams &>(parent->params());
 
    readLinearHist
        .init(p.linear_hist_bins)
        .flags(parent->disableLinearHists ? nozero : pdf);
 
    readLogHist
        .init(p.log_hist_bins)
        .flags(parent->disableLogHists ? nozero : pdf);
 
    writeLinearHist
        .init(p.linear_hist_bins)
        .flags(parent->disableLinearHists ? nozero : pdf);
 
    writeLogHist
        .init(p.log_hist_bins)
        .flags(parent->disableLogHists ? nozero : pdf);
 
    infiniteSD
        .flags(nozero);
}
 
void
StackDistProbe::handleRequest(const probing::PacketInfo &pkt_info)
{
    // only capturing read and write requests (which allocate in the
    // cache)
    if (!pkt_info.cmd.isRead() && !pkt_info.cmd.isWrite())
        return;
 
    // Align the address to a cache line size
    const Addr aligned_addr(roundDown(pkt_info.addr, lineSize));
 
    // Calculate the stack distance
    const uint64_t sd(calc.calcStackDistAndUpdate(aligned_addr).first);
    if (sd == StackDistCalc::Infinity) {
        stats.infiniteSD++;
        return;
    }
 
    // Sample the stack distance of the address in linear bins
    if (!disableLinearHists) {
        if (pkt_info.cmd.isRead())
            stats.readLinearHist.sample(sd);
        else
            stats.writeLinearHist.sample(sd);
    }
 
    if (!disableLogHists) {
        int sd_lg2 = sd == 0 ? 1 : floorLog2(sd);
 
        // Sample the stack distance of the address in log bins
        if (pkt_info.cmd.isRead())
            stats.readLogHist.sample(sd_lg2);
        else
            stats.writeLogHist.sample(sd_lg2);
    }
}
 
} // namespace gem5