src/mem/cache/coherence/uni_coherence.cc

   1 /*
   2  * Copyright (c) 2003-2005 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Erik Hallnor
  29  */
  30
  31 #include "mem/cache/coherence/uni_coherence.hh"
  32 #include "mem/cache/base_cache.hh"
  33
  34 #include "base/trace.hh"
  35
  36 using namespace std;
  37
  38 UniCoherence::UniCoherence()
  39     : cshrs(50)
  40 {
  41 }
  42
  43 Packet *
  44 UniCoherence::getPacket()
  45 {
  46     bool unblock = cshrs.isFull();
  47     Packet* pkt = cshrs.getReq();
  48     cshrs.markInService((MSHR*)pkt->senderState);
  49     if (!cshrs.havePending()) {
  50         cache->clearSlaveRequest(Request_Coherence);
  51     }
  52     if (unblock) {
  53         //since CSHRs are always used as buffers, should always get rid of one
  54         assert(!cshrs.isFull());
  55         cache->clearBlocked(Blocked_Coherence);
  56     }
  57     return pkt;
  58 }
  59
  60 /**
  61  * @todo add support for returning slave requests, not doing them here.
  62  */
  63 bool
  64 UniCoherence::handleBusRequest(Packet * &pkt, CacheBlk *blk, MSHR *mshr,
  65                                CacheBlk::State &new_state)
  66 {
  67     new_state = 0;
  68     if (pkt->isInvalidate()) {
  69         DPRINTF(Cache, "snoop inval on blk %x (blk ptr %x)\n",
  70                 pkt->getAddr(), blk);
  71         // Forward to other caches
  72         Packet * tmp = new Packet(pkt->req, Packet::InvalidateReq, -1);
  73         cshrs.allocate(tmp);
  74         cache->setSlaveRequest(Request_Coherence, curTick);
  75         if (cshrs.isFull()) {
  76             cache->setBlockedForSnoop(Blocked_Coherence);
  77         }
  78     } else {
  79         if (blk) {
  80             new_state = blk->status;
  81         }
  82     }
  83     return false;
  84 }