src/mem/ruby/system/VIPERCoalescer.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2013-2015 Advanced Micro Devices, Inc.
  * All rights reserved.
  *
  * For use for simulation and test purposes only
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
  * this list of conditions and the following disclaimer.
  *
  * 2. 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.
  *
  * 3. Neither the name of the copyright holder 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 HOLDER 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 "base/logging.hh"
 #include "base/str.hh"
 #include "config/the_isa.hh"

 #if THE_ISA == X86_ISA
 #include "arch/x86/insts/microldstop.hh"

 #endif // X86_ISA
 #include "mem/ruby/system/VIPERCoalescer.hh"

 #include "cpu/testers/rubytest/RubyTester.hh"
 #include "debug/GPUCoalescer.hh"
 #include "debug/MemoryAccess.hh"
 #include "debug/ProtocolTrace.hh"
 #include "mem/packet.hh"
 #include "mem/ruby/common/SubBlock.hh"
 #include "mem/ruby/network/MessageBuffer.hh"
 #include "mem/ruby/profiler/Profiler.hh"
 #include "mem/ruby/slicc_interface/AbstractController.hh"
 #include "mem/ruby/slicc_interface/RubyRequest.hh"
 #include "mem/ruby/structures/CacheMemory.hh"
 #include "mem/ruby/system/GPUCoalescer.hh"
 #include "mem/ruby/system/RubySystem.hh"
 #include "params/VIPERCoalescer.hh"

 using namespace std;

 VIPERCoalescer *
 VIPERCoalescerParams::create()
 {
     return new VIPERCoalescer(this);
 }

 VIPERCoalescer::VIPERCoalescer(const Params *p)
     : GPUCoalescer(p),
       m_cache_inv_pkt(nullptr),
       m_num_pending_invs(0)
 {
 }

 VIPERCoalescer::~VIPERCoalescer()
 {
 }

 // Places an uncoalesced packet in uncoalescedTable. If the packet is a
 // special type (MemFence, scoping, etc), it is issued immediately.
 RequestStatus
 VIPERCoalescer::makeRequest(PacketPtr pkt)
 {
     // VIPER only supports following memory request types
     //    MemSyncReq & Acquire: TCP cache invalidation
     //    ReadReq             : cache read
     //    WriteReq            : cache write
     //    AtomicOp            : cache atomic
     //
     // VIPER does not expect MemSyncReq & Release since in GCN3, compute unit
     // does not specify an equivalent type of memory request.
     // TODO: future patches should rename Acquire and Release
     assert((pkt->cmd == MemCmd::MemSyncReq && pkt->req->isAcquire()) ||
             pkt->cmd == MemCmd::ReadReq ||
             pkt->cmd == MemCmd::WriteReq ||
             pkt->isAtomicOp());

     if (pkt->req->isAcquire() && m_cache_inv_pkt) {
         // In VIPER protocol, the coalescer is not able to handle two or
         // more cache invalidation requests at a time. Cache invalidation
         // requests must be serialized to ensure that all stale data in
         // TCP are invalidated correctly. If there's already a pending
         // cache invalidation request, we must retry this request later
         return RequestStatus_Aliased;
     }

     GPUCoalescer::makeRequest(pkt);

     if (pkt->req->isAcquire()) {
         // In VIPER protocol, a compute unit sends a MemSyncReq with Acquire
         // flag to invalidate TCP. Upon receiving a request of this type,
         // VIPERCoalescer starts a cache walk to invalidate all valid entries
         // in TCP. The request is completed once all entries are invalidated.
         assert(!m_cache_inv_pkt);
         m_cache_inv_pkt = pkt;
         invTCP();
     }

     return RequestStatus_Issued;
 }

 void
 VIPERCoalescer::issueRequest(CoalescedRequest* crequest)
 {
     PacketPtr pkt = crequest->getFirstPkt();

     int proc_id = -1;
     if (pkt != NULL && pkt->req->hasContextId()) {
         proc_id = pkt->req->contextId();
     }

     // If valid, copy the pc to the ruby request
     Addr pc = 0;
     if (pkt->req->hasPC()) {
         pc = pkt->req->getPC();
     }

     Addr line_addr = makeLineAddress(pkt->getAddr());

     // Creating WriteMask that records written bytes
     // and atomic operations. This enables partial writes
     // and partial reads of those writes
     DataBlock dataBlock;
     dataBlock.clear();
     uint32_t blockSize = RubySystem::getBlockSizeBytes();
     std::vector<bool> accessMask(blockSize,false);
     std::vector< std::pair<int,AtomicOpFunctor*> > atomicOps;
     uint32_t tableSize = crequest->getPackets().size();
     for (int i = 0; i < tableSize; i++) {
         PacketPtr tmpPkt = crequest->getPackets()[i];
         uint32_t tmpOffset = (tmpPkt->getAddr()) - line_addr;
         uint32_t tmpSize = tmpPkt->getSize();
         if (tmpPkt->isAtomicOp()) {
             std::pair<int,AtomicOpFunctor *> tmpAtomicOp(tmpOffset,
                                                         tmpPkt->getAtomicOp());
             atomicOps.push_back(tmpAtomicOp);
         } else if (tmpPkt->isWrite()) {
             dataBlock.setData(tmpPkt->getPtr<uint8_t>(),
                               tmpOffset, tmpSize);
         }
         for (int j = 0; j < tmpSize; j++) {
             accessMask[tmpOffset + j] = true;
         }
     }
     std::shared_ptr<RubyRequest> msg;
     if (pkt->isAtomicOp()) {
         msg = std::make_shared<RubyRequest>(clockEdge(), pkt->getAddr(),
                               pkt->getPtr<uint8_t>(),
                               pkt->getSize(), pc, crequest->getRubyType(),
                               RubyAccessMode_Supervisor, pkt,
                               PrefetchBit_No, proc_id, 100,
                               blockSize, accessMask,
                               dataBlock, atomicOps, crequest->getSeqNum());
     } else {
         msg = std::make_shared<RubyRequest>(clockEdge(), pkt->getAddr(),
                               pkt->getPtr<uint8_t>(),
                               pkt->getSize(), pc, crequest->getRubyType(),
                               RubyAccessMode_Supervisor, pkt,
                               PrefetchBit_No, proc_id, 100,
                               blockSize, accessMask,
                               dataBlock, crequest->getSeqNum());
     }

     if (pkt->cmd == MemCmd::WriteReq) {
         makeWriteCompletePkts(crequest);
     }

     DPRINTFR(ProtocolTrace, "%15s %3s %10s%20s %6s>%-6s %s %s\n",
              curTick(), m_version, "Coal", "Begin", "", "",
              printAddress(msg->getPhysicalAddress()),
              RubyRequestType_to_string(crequest->getRubyType()));

     fatal_if(crequest->getRubyType() == RubyRequestType_IFETCH,
              "there should not be any I-Fetch requests in the GPU Coalescer");

     if (!deadlockCheckEvent.scheduled()) {
         schedule(deadlockCheckEvent,
                  m_deadlock_threshold * clockPeriod() +
                  curTick());
     }

     assert(m_mandatory_q_ptr);
     Tick latency = cyclesToTicks(
         m_controller->mandatoryQueueLatency(crequest->getRubyType()));
     m_mandatory_q_ptr->enqueue(msg, clockEdge(), latency);
 }

 void
 VIPERCoalescer::makeWriteCompletePkts(CoalescedRequest* crequest)
 {
     // In VIPER protocol, for each write request, down-stream caches
     // return two responses: writeCallback and writeCompleteCallback.
     // We need to prepare a writeCompletePkt for each write request so
     // that when writeCompleteCallback is called, we can respond
     // requesting wavefront right away.
     // writeCompletePkt inherits request and senderState of the original
     // write request packet so that we can find the original requestor
     // later. This assumes that request and senderState are not deleted
     // before writeCompleteCallback is called.

     auto key = crequest->getSeqNum();
     std::vector<PacketPtr>& req_pkts = crequest->getPackets();

     for (auto pkt : req_pkts) {
         DPRINTF(GPUCoalescer, "makeWriteCompletePkts: instSeqNum %d\n",
                 key);
         assert(pkt->cmd == MemCmd::WriteReq);

         PacketPtr writeCompletePkt = new Packet(pkt->req,
             MemCmd::WriteCompleteResp);
         writeCompletePkt->setAddr(pkt->getAddr());
         writeCompletePkt->senderState = pkt->senderState;
         m_writeCompletePktMap[key].push_back(writeCompletePkt);
     }
 }

 void
 VIPERCoalescer::writeCompleteCallback(Addr addr, uint64_t instSeqNum)
 {
     DPRINTF(GPUCoalescer, "writeCompleteCallback: instSeqNum %d addr 0x%x\n",
             instSeqNum, addr);

     auto key = instSeqNum;
     assert(m_writeCompletePktMap.count(key) == 1 &&
            !m_writeCompletePktMap[key].empty());

     for (auto writeCompletePkt : m_writeCompletePktMap[key]) {
         if (makeLineAddress(writeCompletePkt->getAddr()) == addr) {
             RubyPort::SenderState *ss =
                 safe_cast<RubyPort::SenderState *>
                     (writeCompletePkt->senderState);
             MemSlavePort *port = ss->port;
             assert(port != NULL);

             writeCompletePkt->senderState = ss->predecessor;
             delete ss;
             port->hitCallback(writeCompletePkt);
         }
     }

     trySendRetries();

     if (m_writeCompletePktMap[key].empty())
         m_writeCompletePktMap.erase(key);
 }

 void
 VIPERCoalescer::invTCPCallback(Addr addr)
 {
     assert(m_cache_inv_pkt && m_num_pending_invs > 0);

     m_num_pending_invs--;

     if (m_num_pending_invs == 0) {
         std::vector<PacketPtr> pkt_list { m_cache_inv_pkt };
         completeHitCallback(pkt_list);
         m_cache_inv_pkt = nullptr;
     }
 }

 /**
   * Invalidate TCP (Acquire)
   */
 void
 VIPERCoalescer::invTCP()
 {
     int size = m_dataCache_ptr->getNumBlocks();
     DPRINTF(GPUCoalescer,
             "There are %d Invalidations outstanding before Cache Walk\n",
             m_num_pending_invs);
     // Walk the cache
     for (int i = 0; i < size; i++) {
         Addr addr = m_dataCache_ptr->getAddressAtIdx(i);
         // Evict Read-only data
         RubyRequestType request_type = RubyRequestType_REPLACEMENT;
         std::shared_ptr<RubyRequest> msg = std::make_shared<RubyRequest>(
             clockEdge(), addr, (uint8_t*) 0, 0, 0,
             request_type, RubyAccessMode_Supervisor,
             nullptr);
         DPRINTF(GPUCoalescer, "Evicting addr 0x%x\n", addr);
         assert(m_mandatory_q_ptr != NULL);
         Tick latency = cyclesToTicks(
             m_controller->mandatoryQueueLatency(request_type));
         m_mandatory_q_ptr->enqueue(msg, clockEdge(), latency);
         m_num_pending_invs++;
     }
     DPRINTF(GPUCoalescer,
             "There are %d Invalidatons outstanding after Cache Walk\n",
             m_num_pending_invs);
 }
	/*
	* Copyright (c) 2013-2015 Advanced Micro Devices, Inc.
	* All rights reserved.
	*
	* For use for simulation and test purposes only
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright notice,
	* this list of conditions and the following disclaimer.
	*
	* 2. 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.
	*
	* 3. Neither the name of the copyright holder 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 HOLDER 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 "base/logging.hh"
	#include "base/str.hh"
	#include "config/the_isa.hh"

	#if THE_ISA == X86_ISA
	#include "arch/x86/insts/microldstop.hh"

	#endif // X86_ISA
	#include "mem/ruby/system/VIPERCoalescer.hh"

	#include "cpu/testers/rubytest/RubyTester.hh"
	#include "debug/GPUCoalescer.hh"
	#include "debug/MemoryAccess.hh"
	#include "debug/ProtocolTrace.hh"
	#include "mem/packet.hh"
	#include "mem/ruby/common/SubBlock.hh"
	#include "mem/ruby/network/MessageBuffer.hh"
	#include "mem/ruby/profiler/Profiler.hh"
	#include "mem/ruby/slicc_interface/AbstractController.hh"
	#include "mem/ruby/slicc_interface/RubyRequest.hh"
	#include "mem/ruby/structures/CacheMemory.hh"
	#include "mem/ruby/system/GPUCoalescer.hh"
	#include "mem/ruby/system/RubySystem.hh"
	#include "params/VIPERCoalescer.hh"

	using namespace std;

	VIPERCoalescer *
	VIPERCoalescerParams::create()
	{
	return new VIPERCoalescer(this);
	}

	VIPERCoalescer::VIPERCoalescer(const Params *p)
	: GPUCoalescer(p),
	m_cache_inv_pkt(nullptr),
	m_num_pending_invs(0)
	{
	}

	VIPERCoalescer::~VIPERCoalescer()
	{
	}

	// Places an uncoalesced packet in uncoalescedTable. If the packet is a
	// special type (MemFence, scoping, etc), it is issued immediately.
	RequestStatus
	VIPERCoalescer::makeRequest(PacketPtr pkt)
	{
	// VIPER only supports following memory request types
	// MemSyncReq & Acquire: TCP cache invalidation
	// ReadReq : cache read
	// WriteReq : cache write
	// AtomicOp : cache atomic
	//
	// VIPER does not expect MemSyncReq & Release since in GCN3, compute unit
	// does not specify an equivalent type of memory request.
	// TODO: future patches should rename Acquire and Release
	assert((pkt->cmd == MemCmd::MemSyncReq && pkt->req->isAcquire()) \|\|
	pkt->cmd == MemCmd::ReadReq \|\|
	pkt->cmd == MemCmd::WriteReq \|\|
	pkt->isAtomicOp());

	if (pkt->req->isAcquire() && m_cache_inv_pkt) {
	// In VIPER protocol, the coalescer is not able to handle two or
	// more cache invalidation requests at a time. Cache invalidation
	// requests must be serialized to ensure that all stale data in
	// TCP are invalidated correctly. If there's already a pending
	// cache invalidation request, we must retry this request later
	return RequestStatus_Aliased;
	}

	GPUCoalescer::makeRequest(pkt);

	if (pkt->req->isAcquire()) {
	// In VIPER protocol, a compute unit sends a MemSyncReq with Acquire
	// flag to invalidate TCP. Upon receiving a request of this type,
	// VIPERCoalescer starts a cache walk to invalidate all valid entries
	// in TCP. The request is completed once all entries are invalidated.
	assert(!m_cache_inv_pkt);
	m_cache_inv_pkt = pkt;
	invTCP();
	}

	return RequestStatus_Issued;
	}

	void
	VIPERCoalescer::issueRequest(CoalescedRequest* crequest)
	{
	PacketPtr pkt = crequest->getFirstPkt();

	int proc_id = -1;
	if (pkt != NULL && pkt->req->hasContextId()) {
	proc_id = pkt->req->contextId();
	}

	// If valid, copy the pc to the ruby request
	Addr pc = 0;
	if (pkt->req->hasPC()) {
	pc = pkt->req->getPC();
	}

	Addr line_addr = makeLineAddress(pkt->getAddr());

	// Creating WriteMask that records written bytes
	// and atomic operations. This enables partial writes
	// and partial reads of those writes
	DataBlock dataBlock;
	dataBlock.clear();
	uint32_t blockSize = RubySystem::getBlockSizeBytes();
	std::vector<bool> accessMask(blockSize,false);
	std::vector< std::pair<int,AtomicOpFunctor*> > atomicOps;
	uint32_t tableSize = crequest->getPackets().size();
	for (int i = 0; i < tableSize; i++) {
	PacketPtr tmpPkt = crequest->getPackets()[i];
	uint32_t tmpOffset = (tmpPkt->getAddr()) - line_addr;
	uint32_t tmpSize = tmpPkt->getSize();
	if (tmpPkt->isAtomicOp()) {
	std::pair<int,AtomicOpFunctor *> tmpAtomicOp(tmpOffset,
	tmpPkt->getAtomicOp());
	atomicOps.push_back(tmpAtomicOp);
	} else if (tmpPkt->isWrite()) {
	dataBlock.setData(tmpPkt->getPtr<uint8_t>(),
	tmpOffset, tmpSize);
	}
	for (int j = 0; j < tmpSize; j++) {
	accessMask[tmpOffset + j] = true;
	}
	}
	std::shared_ptr<RubyRequest> msg;
	if (pkt->isAtomicOp()) {
	msg = std::make_shared<RubyRequest>(clockEdge(), pkt->getAddr(),
	pkt->getPtr<uint8_t>(),
	pkt->getSize(), pc, crequest->getRubyType(),
	RubyAccessMode_Supervisor, pkt,
	PrefetchBit_No, proc_id, 100,
	blockSize, accessMask,
	dataBlock, atomicOps, crequest->getSeqNum());
	} else {
	msg = std::make_shared<RubyRequest>(clockEdge(), pkt->getAddr(),
	pkt->getPtr<uint8_t>(),
	pkt->getSize(), pc, crequest->getRubyType(),
	RubyAccessMode_Supervisor, pkt,
	PrefetchBit_No, proc_id, 100,
	blockSize, accessMask,
	dataBlock, crequest->getSeqNum());
	}

	if (pkt->cmd == MemCmd::WriteReq) {
	makeWriteCompletePkts(crequest);
	}

	DPRINTFR(ProtocolTrace, "%15s %3s %10s%20s %6s>%-6s %s %s\n",
	curTick(), m_version, "Coal", "Begin", "", "",
	printAddress(msg->getPhysicalAddress()),
	RubyRequestType_to_string(crequest->getRubyType()));

	fatal_if(crequest->getRubyType() == RubyRequestType_IFETCH,
	"there should not be any I-Fetch requests in the GPU Coalescer");

	if (!deadlockCheckEvent.scheduled()) {
	schedule(deadlockCheckEvent,
	m_deadlock_threshold * clockPeriod() +
	curTick());
	}

	assert(m_mandatory_q_ptr);
	Tick latency = cyclesToTicks(
	m_controller->mandatoryQueueLatency(crequest->getRubyType()));
	m_mandatory_q_ptr->enqueue(msg, clockEdge(), latency);
	}

	void
	VIPERCoalescer::makeWriteCompletePkts(CoalescedRequest* crequest)
	{
	// In VIPER protocol, for each write request, down-stream caches
	// return two responses: writeCallback and writeCompleteCallback.
	// We need to prepare a writeCompletePkt for each write request so
	// that when writeCompleteCallback is called, we can respond
	// requesting wavefront right away.
	// writeCompletePkt inherits request and senderState of the original
	// write request packet so that we can find the original requestor
	// later. This assumes that request and senderState are not deleted
	// before writeCompleteCallback is called.

	auto key = crequest->getSeqNum();
	std::vector<PacketPtr>& req_pkts = crequest->getPackets();

	for (auto pkt : req_pkts) {
	DPRINTF(GPUCoalescer, "makeWriteCompletePkts: instSeqNum %d\n",
	key);
	assert(pkt->cmd == MemCmd::WriteReq);

	PacketPtr writeCompletePkt = new Packet(pkt->req,
	MemCmd::WriteCompleteResp);
	writeCompletePkt->setAddr(pkt->getAddr());
	writeCompletePkt->senderState = pkt->senderState;
	m_writeCompletePktMap[key].push_back(writeCompletePkt);
	}
	}

	void
	VIPERCoalescer::writeCompleteCallback(Addr addr, uint64_t instSeqNum)
	{
	DPRINTF(GPUCoalescer, "writeCompleteCallback: instSeqNum %d addr 0x%x\n",
	instSeqNum, addr);

	auto key = instSeqNum;
	assert(m_writeCompletePktMap.count(key) == 1 &&
	!m_writeCompletePktMap[key].empty());

	for (auto writeCompletePkt : m_writeCompletePktMap[key]) {
	if (makeLineAddress(writeCompletePkt->getAddr()) == addr) {
	RubyPort::SenderState *ss =
	safe_cast<RubyPort::SenderState *>
	(writeCompletePkt->senderState);
	MemSlavePort *port = ss->port;
	assert(port != NULL);

	writeCompletePkt->senderState = ss->predecessor;
	delete ss;
	port->hitCallback(writeCompletePkt);
	}
	}

	trySendRetries();

	if (m_writeCompletePktMap[key].empty())
	m_writeCompletePktMap.erase(key);
	}

	void
	VIPERCoalescer::invTCPCallback(Addr addr)
	{
	assert(m_cache_inv_pkt && m_num_pending_invs > 0);

	m_num_pending_invs--;

	if (m_num_pending_invs == 0) {
	std::vector<PacketPtr> pkt_list { m_cache_inv_pkt };
	completeHitCallback(pkt_list);
	m_cache_inv_pkt = nullptr;
	}
	}

	/**
	* Invalidate TCP (Acquire)
	*/
	void
	VIPERCoalescer::invTCP()
	{
	int size = m_dataCache_ptr->getNumBlocks();
	DPRINTF(GPUCoalescer,
	"There are %d Invalidations outstanding before Cache Walk\n",
	m_num_pending_invs);
	// Walk the cache
	for (int i = 0; i < size; i++) {
	Addr addr = m_dataCache_ptr->getAddressAtIdx(i);
	// Evict Read-only data
	RubyRequestType request_type = RubyRequestType_REPLACEMENT;
	std::shared_ptr<RubyRequest> msg = std::make_shared<RubyRequest>(
	clockEdge(), addr, (uint8_t*) 0, 0, 0,
	request_type, RubyAccessMode_Supervisor,
	nullptr);
	DPRINTF(GPUCoalescer, "Evicting addr 0x%x\n", addr);
	assert(m_mandatory_q_ptr != NULL);
	Tick latency = cyclesToTicks(
	m_controller->mandatoryQueueLatency(request_type));
	m_mandatory_q_ptr->enqueue(msg, clockEdge(), latency);
	m_num_pending_invs++;
	}
	DPRINTF(GPUCoalescer,
	"There are %d Invalidatons outstanding after Cache Walk\n",
	m_num_pending_invs);
	}