gem5/src/gpu-compute/lds_state.cc
Tony Gutierrez 7ac38849ab gpu-compute: remove inst enums and use bit flag for attributes
this patch removes the GPUStaticInst enums that were defined in GPU.py.
instead, a simple set of attribute flags that can be set in the base
instruction class are used. this will help unify the attributes of HSAIL
and machine ISA instructions within the model itself.

because the static instrution now carries the attributes, a GPUDynInst
must carry a pointer to a valid GPUStaticInst so a new static kernel launch
instruction is added, which carries the attributes needed to perform a
the kernel launch.
2016-10-26 22:47:11 -04:00

332 lines
10 KiB
C++

/*
* 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.
*
* Author: John Kalamatianos, Joe Gross
*/
#include "gpu-compute/lds_state.hh"
#include <array>
#include <cstdio>
#include <cstdlib>
#include "gpu-compute/compute_unit.hh"
#include "gpu-compute/gpu_dyn_inst.hh"
#include "gpu-compute/shader.hh"
/**
* the default constructor that works with SWIG
*/
LdsState::LdsState(const Params *params) :
MemObject(params),
tickEvent(this),
cuPort(name() + ".port", this),
maximumSize(params->size),
range(params->range),
bankConflictPenalty(params->bankConflictPenalty),
banks(params->banks)
{
fatal_if(params->banks <= 0,
"Number of LDS banks should be positive number");
fatal_if((params->banks & (params->banks - 1)) != 0,
"Number of LDS banks should be a power of 2");
fatal_if(params->size <= 0,
"cannot allocate an LDS with a size less than 1");
fatal_if(params->size % 2,
"the LDS should be an even number");
}
/**
* Needed by the SWIG compiler
*/
LdsState *
LdsStateParams::create()
{
return new LdsState(this);
}
/**
* set the parent and name based on the parent
*/
void
LdsState::setParent(ComputeUnit *x_parent)
{
// check that this gets assigned to the same thing each time
fatal_if(!x_parent, "x_parent should not be nullptr");
fatal_if(x_parent == parent,
"should not be setting the parent twice");
parent = x_parent;
_name = x_parent->name() + ".LdsState";
}
/**
* derive the gpu mem packet from the packet and then count the bank conflicts
*/
unsigned
LdsState::countBankConflicts(PacketPtr packet, unsigned *bankAccesses)
{
Packet::SenderState *baseSenderState = packet->senderState;
while (baseSenderState->predecessor) {
baseSenderState = baseSenderState->predecessor;
}
const ComputeUnit::LDSPort::SenderState *senderState =
dynamic_cast<ComputeUnit::LDSPort::SenderState *>(baseSenderState);
fatal_if(!senderState,
"did not get the right sort of sender state");
GPUDynInstPtr gpuDynInst = senderState->getMemInst();
return countBankConflicts(gpuDynInst, bankAccesses);
}
// Count the total number of bank conflicts for the local memory packet
unsigned
LdsState::countBankConflicts(GPUDynInstPtr gpuDynInst,
unsigned *numBankAccesses)
{
int bank_conflicts = 0;
std::vector<int> bank;
// the number of LDS banks being touched by the memory instruction
int numBanks = std::min(parent->wfSize(), banks);
// if the wavefront size is larger than the number of LDS banks, we
// need to iterate over all work items to calculate the total
// number of bank conflicts
int groups = (parent->wfSize() > numBanks) ?
(parent->wfSize() / numBanks) : 1;
for (int i = 0; i < groups; i++) {
// Address Array holding all the work item addresses of an instruction
std::vector<Addr> addr_array;
addr_array.resize(numBanks, 0);
bank.clear();
bank.resize(banks, 0);
int max_bank = 0;
// populate the address array for all active work items
for (int j = 0; j < numBanks; j++) {
if (gpuDynInst->exec_mask[(i*numBanks)+j]) {
addr_array[j] = gpuDynInst->addr[(i*numBanks)+j];
} else {
addr_array[j] = std::numeric_limits<Addr>::max();
}
}
if (gpuDynInst->isLoad() || gpuDynInst->isStore()) {
// mask identical addresses
for (int j = 0; j < numBanks; ++j) {
for (int j0 = 0; j0 < j; j0++) {
if (addr_array[j] != std::numeric_limits<Addr>::max()
&& addr_array[j] == addr_array[j0]) {
addr_array[j] = std::numeric_limits<Addr>::max();
}
}
}
}
// calculate bank conflicts
for (int j = 0; j < numBanks; ++j) {
if (addr_array[j] != std::numeric_limits<Addr>::max()) {
int bankId = addr_array[j] % banks;
bank[bankId]++;
max_bank = std::max(max_bank, bank[bankId]);
// Count the number of LDS banks accessed.
// Since we have masked identical addresses all remaining
// accesses will need to be serialized if they access
// the same bank (bank conflict).
(*numBankAccesses)++;
}
}
bank_conflicts += max_bank;
}
panic_if(bank_conflicts > parent->wfSize(),
"Max bank conflicts should match num of work items per instr");
return bank_conflicts;
}
/**
* receive the packet from the CU
*/
bool
LdsState::CuSidePort::recvTimingReq(PacketPtr packet)
{
return ownerLds->processPacket(packet);
}
GPUDynInstPtr
LdsState::getDynInstr(PacketPtr packet)
{
ComputeUnit::LDSPort::SenderState *ss =
dynamic_cast<ComputeUnit::LDSPort::SenderState *>(
packet->senderState);
return ss->getMemInst();
}
/**
* process an incoming packet, add it to the return queue
*/
bool
LdsState::processPacket(PacketPtr packet)
{
unsigned bankAccesses = 0;
// the number of conflicts this packet will have when accessing the LDS
unsigned bankConflicts = countBankConflicts(packet, &bankAccesses);
// count the total number of physical LDS bank accessed
parent->ldsBankAccesses += bankAccesses;
// count the LDS bank conflicts. A number set to 1 indicates one
// access per bank maximum so there are no bank conflicts
parent->ldsBankConflictDist.sample(bankConflicts-1);
GPUDynInstPtr dynInst = getDynInstr(packet);
// account for the LDS bank conflict overhead
int busLength = (dynInst->isLoad()) ? parent->loadBusLength() :
(dynInst->isStore()) ? parent->storeBusLength() :
parent->loadBusLength();
// delay for accessing the LDS
Tick processingTime =
parent->shader->ticks(bankConflicts * bankConflictPenalty) +
parent->shader->ticks(busLength);
// choose (delay + last packet in queue) or (now + delay) as the time to
// return this
Tick doneAt = earliestReturnTime() + processingTime;
// then store it for processing
return returnQueuePush(std::make_pair(doneAt, packet));
}
/**
* add this to the queue of packets to be returned
*/
bool
LdsState::returnQueuePush(std::pair<Tick, PacketPtr> thePair)
{
// TODO add time limits (e.g. one packet per cycle) and queue size limits
// and implement flow control
returnQueue.push(thePair);
// if there is no set wakeup time, look through the queue
if (!tickEvent.scheduled()) {
process();
}
return true;
}
/**
* receive a packet in functional mode
*/
void
LdsState::CuSidePort::recvFunctional(PacketPtr pkt)
{
fatal("not implemented");
}
/**
* receive a retry for a response
*/
void
LdsState::CuSidePort::recvRespRetry()
{
// TODO verify that this is the right way to do this
assert(ownerLds->isRetryResp());
ownerLds->setRetryResp(false);
ownerLds->process();
}
/**
* receive a retry
*/
void
LdsState::CuSidePort::recvRetry()
{
fatal("not implemented");
}
/**
* look for packets to return at this time
*/
bool
LdsState::process()
{
Tick now = clockEdge();
// send back completed packets
while (!returnQueue.empty() && returnQueue.front().first <= now) {
PacketPtr packet = returnQueue.front().second;
ComputeUnit::LDSPort::SenderState *ss =
dynamic_cast<ComputeUnit::LDSPort::SenderState *>(
packet->senderState);
GPUDynInstPtr gpuDynInst = ss->getMemInst();
gpuDynInst->initiateAcc(gpuDynInst);
packet->makeTimingResponse();
returnQueue.pop();
bool success = cuPort.sendTimingResp(packet);
if (!success) {
retryResp = true;
panic("have not handled timing responses being NACK'd when sent"
"back");
}
}
// determine the next wakeup time
if (!returnQueue.empty()) {
Tick next = returnQueue.front().first;
if (tickEvent.scheduled()) {
if (next < tickEvent.when()) {
tickEvent.deschedule();
tickEvent.schedule(next);
}
} else {
tickEvent.schedule(next);
}
}
return true;
}
/**
* wake up at this time and perform specified actions
*/
void
LdsState::TickEvent::process()
{
ldsState->process();
}