ghb.cc

来自「M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作」· CC 代码 · 共 75 行

/*
 * Copyright (c) 2005
 * The Regents of The University of Michigan
 * All Rights Reserved
 *
 * This code is part of the M5 simulator.
 *
 * Permission is granted to use, copy, create derivative works and
 * redistribute this software and such derivative works for any
 * purpose, so long as the copyright notice above, this grant of
 * permission, and the disclaimer below appear in all copies made; and
 * so long as the name of The University of Michigan is not used in
 * any advertising or publicity pertaining to the use or distribution
 * of this software without specific, written prior authorization.
 *
 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE
 * UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND
 * WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE
 * LIABLE FOR ANY DAMAGES, INCLUDING DIRECT, SPECIAL, INDIRECT,
 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM
 * ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGES.
 *
 * Authors: Ronald G. Dreslinski Jr
 *          Steven K. Reinhardt
 */

/**
 * @file
 * GHB Prefetcher implementation.
 */

#include "mem/cache/prefetch/ghb.hh"
#include "arch/isa_traits.hh"

void
GHBPrefetcher::calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses,
                                 std::list<Tick> &delays)
{
    Addr blkAddr = pkt->getAddr() & ~(Addr)(this->blkSize-1);
    int cpuID = pkt->req->getCpuNum();
    if (!useCPUId) cpuID = 0;


    int new_stride = blkAddr - last_miss_addr[cpuID];
    int old_stride = last_miss_addr[cpuID] -
        second_last_miss_addr[cpuID];

    second_last_miss_addr[cpuID] = last_miss_addr[cpuID];
    last_miss_addr[cpuID] = blkAddr;

    if (new_stride == old_stride) {
        for (int d=1; d <= degree; d++) {
            Addr newAddr = blkAddr + d * new_stride;
            if (this->pageStop &&
                (blkAddr & ~(TheISA::VMPageSize - 1)) !=
                (newAddr & ~(TheISA::VMPageSize - 1)))
            {
                //Spanned the page, so now stop
                this->pfSpanPage += degree - d + 1;
                return;
            }
            else
            {
                addresses.push_back(newAddr);
                delays.push_back(latency);
            }
        }
    }
}