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/*
* Copyright (c) 2014-2015 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.
*
* Authors: John Kalamatianos,
* Sooraj Puthoor
*/
#ifndef __GLOBAL_MEMORY_PIPELINE_HH__
#define __GLOBAL_MEMORY_PIPELINE_HH__
#include <queue>
#include <string>
#include "gpu-compute/misc.hh"
#include "params/ComputeUnit.hh"
#include "sim/stats.hh"
/*
* @file global_memory_pipeline.hh
*
* The global memory pipeline issues newly created global memory packets
* from the pipeline to DTLB. The exec() method of the memory packet issues
* the packet to the DTLB if there is space available in the return fifo.
* This stage also retires previously issued loads and stores that have
* returned from the memory sub-system.
*/
class ComputeUnit;
class GlobalMemPipeline
{
public:
GlobalMemPipeline(const ComputeUnitParams *params);
void init(ComputeUnit *cu);
void exec();
std::queue<GPUDynInstPtr> &getGMStRespFIFO() { return gmReturnedStores; }
std::queue<GPUDynInstPtr> &getGMLdRespFIFO() { return gmReturnedLoads; }
/**
* find the next ready response to service. for OoO mode we
* simply pop the oldest (based on when the response was
* received) response in the response FIFOs. for in-order mode
* we pop the oldest (in program order) response, and only if
* it is marked as done.
*/
GPUDynInstPtr getNextReadyResp();
/**
* once a memory request is finished we remove it from the
* buffer. this method determines which response buffer
* we're using based on the mode (in-order vs. OoO).
*/
void completeRequest(GPUDynInstPtr gpuDynInst);
/**
* issues a request to the pipeline - i.e., enqueue it
* in the request buffer.
*/
void issueRequest(GPUDynInstPtr gpuDynInst);
/**
* this method handles responses sent to this GM pipeline by the
* CU. in the case of in-order delivery it simply marks the reqeust
* as done in the ordered buffer to indicate that the requst is
* finished. for out-of-order data delivery, the requests are enqueued
* (in the order in which they are received) in the response FIFOs.
*/
void handleResponse(GPUDynInstPtr gpuDynInst);
bool
isGMLdRespFIFOWrRdy() const
{
return gmReturnedLoads.size() < gmQueueSize;
}
bool
isGMStRespFIFOWrRdy() const
{
return gmReturnedStores.size() < gmQueueSize;
}
bool
isGMReqFIFOWrRdy(uint32_t pendReqs=0) const
{
return (gmIssuedRequests.size() + pendReqs) < gmQueueSize;
}
const std::string &name() const { return _name; }
void regStats();
void
incLoadVRFBankConflictCycles(int num_cycles)
{
loadVrfBankConflictCycles += num_cycles;
}
private:
ComputeUnit *computeUnit;
std::string _name;
int gmQueueSize;
bool outOfOrderDataDelivery;
// number of cycles of delaying the update of a VGPR that is the
// target of a load instruction (or the load component of an atomic)
// The delay is due to VRF bank conflicts
Stats::Scalar loadVrfBankConflictCycles;
// Counters to track the inflight loads and stores
// so that we can provide the proper backpressure
// on the number of inflight memory operations.
int inflightStores;
int inflightLoads;
// The size of global memory.
int globalMemSize;
/*
* this buffer holds the memory responses when in-order data
* deilvery is used - the responses are ordered by their unique
* sequence number, which is monotonically increasing. when a
* memory request returns its "done" flag is set to true. during
* each tick the the GM pipeline will check if the oldest request
* is finished, and if so it will be removed from the queue.
*
* key: memory instruction's sequence ID
*
* value: pair holding the instruction pointer and a bool that
* is used to indicate whether or not the request has
* completed
*/
std::map<uint64_t, std::pair<GPUDynInstPtr, bool>> gmOrderedRespBuffer;
// Global Memory Request FIFO: all global memory requests
// are issued to this FIFO from the memory pipelines
std::queue<GPUDynInstPtr> gmIssuedRequests;
// Globa Store Response FIFO: all responses of global memory
// stores are sent to this FIFO from TCP
std::queue<GPUDynInstPtr> gmReturnedStores;
// Global Load Response FIFO: all responses of global memory
// loads are sent to this FIFO from TCP
std::queue<GPUDynInstPtr> gmReturnedLoads;
};
#endif // __GLOBAL_MEMORY_PIPELINE_HH__
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