src/gpu-compute/dispatcher.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2011-2015,2018 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: Brad Beckmann,
  *          Marc Orr,
  *          Anthony Gutierrez
  */


 #include "gpu-compute/dispatcher.hh"

 #include "cpu/base.hh"
 #include "debug/GPUDisp.hh"
 #include "gpu-compute/cl_driver.hh"
 #include "gpu-compute/cl_event.hh"
 #include "gpu-compute/shader.hh"
 #include "gpu-compute/wavefront.hh"
 #include "mem/packet_access.hh"

 GpuDispatcher *GpuDispatcher::instance = nullptr;

 GpuDispatcher::GpuDispatcher(const Params *p)
     : DmaDevice(p), _masterId(p->system->getMasterId(this, "disp")),
       pioAddr(p->pio_addr), pioSize(4096), pioDelay(p->pio_latency),
       dispatchCount(0), dispatchActive(false), cpu(p->cpu),
       shader(p->shader_pointer), driver(p->cl_driver),
       tickEvent([this]{ exec(); }, "GPU Dispatcher tick",
                 false, Event::CPU_Tick_Pri)
 {
     shader->handshake(this);
     driver->handshake(this);

     ndRange.wg_disp_rem = false;
     ndRange.globalWgId = 0;

     schedule(&tickEvent, 0);

     // translation port for the dispatcher
     tlbPort = new TLBPort(csprintf("%s-port%d", name()), this);

     num_kernelLaunched
     .name(name() + ".num_kernel_launched")
     .desc("number of kernel launched")
     ;
 }

 GpuDispatcher *GpuDispatcherParams::create()
 {
     GpuDispatcher *dispatcher = new GpuDispatcher(this);
     GpuDispatcher::setInstance(dispatcher);

     return GpuDispatcher::getInstance();
 }

 void
 GpuDispatcher::serialize(CheckpointOut &cp) const
 {
     Tick event_tick = 0;

     if (ndRange.wg_disp_rem)
         fatal("Checkpointing not supported during active workgroup execution");

     if (tickEvent.scheduled())
         event_tick = tickEvent.when();

     SERIALIZE_SCALAR(event_tick);

 }

 void
 GpuDispatcher::unserialize(CheckpointIn &cp)
 {
     Tick event_tick;

     if (tickEvent.scheduled())
         deschedule(&tickEvent);

     UNSERIALIZE_SCALAR(event_tick);

     if (event_tick)
         schedule(&tickEvent, event_tick);
 }

 AddrRangeList
 GpuDispatcher::getAddrRanges() const
 {
     AddrRangeList ranges;

     DPRINTF(GPUDisp, "dispatcher registering addr range at %#x size %#x\n",
             pioAddr, pioSize);

     ranges.push_back(RangeSize(pioAddr, pioSize));

     return ranges;
 }

 Tick
 GpuDispatcher::read(PacketPtr pkt)
 {
     assert(pkt->getAddr() >= pioAddr);
     assert(pkt->getAddr() < pioAddr + pioSize);

     int offset = pkt->getAddr() - pioAddr;
     pkt->allocate();

     DPRINTF(GPUDisp, " read register %#x size=%d\n", offset, pkt->getSize());

     if (offset < 8) {
         assert(!offset);
         assert(pkt->getSize() == 8);

         uint64_t retval = dispatchActive;
         pkt->setLE(retval);
     } else {
         offset -= 8;
         assert(offset + pkt->getSize() < sizeof(HsaQueueEntry));
         char *curTaskPtr = (char*)&curTask;

         memcpy(pkt->getPtr<const void*>(), curTaskPtr + offset, pkt->getSize());
     }

     pkt->makeAtomicResponse();

     return pioDelay;
 }

 Tick
 GpuDispatcher::write(PacketPtr pkt)
 {
     assert(pkt->getAddr() >= pioAddr);
     assert(pkt->getAddr() < pioAddr + pioSize);

     int offset = pkt->getAddr() - pioAddr;

 #if TRACING_ON
     uint64_t data_val = 0;

     switch (pkt->getSize()) {
       case 1:
         data_val = pkt->getLE<uint8_t>();
         break;
       case 2:
         data_val = pkt->getLE<uint16_t>();
         break;
       case 4:
         data_val = pkt->getLE<uint32_t>();
         break;
       case 8:
         data_val = pkt->getLE<uint64_t>();
         break;
       default:
         DPRINTF(GPUDisp, "bad size %d\n", pkt->getSize());
     }

     DPRINTF(GPUDisp, "write register %#x value %#x size=%d\n", offset, data_val,
             pkt->getSize());
 #endif
     if (!offset) {
         static int nextId = 0;

         // The depends field of the qstruct, which was previously unused, is
         // used to communicate with simulated application.
         if (curTask.depends) {
             HostState hs;
             shader->ReadMem((uint64_t)(curTask.depends), &hs,
                             sizeof(HostState), 0);

             // update event start time (in nano-seconds)
             uint64_t start = curTick() / 1000;

             shader->WriteMem((uint64_t)(&((_cl_event*)hs.event)->start),
                              &start, sizeof(uint64_t), 0);
         }

         // launch kernel
         ++num_kernelLaunched;

         NDRange *ndr = &(ndRangeMap[nextId]);
         // copy dispatch info
         ndr->q = curTask;

         // update the numDispTask polled by the runtime
         accessUserVar(cpu, (uint64_t)(curTask.numDispLeft), 0, 1);

         ndr->numWgTotal = 1;

         for (int i = 0; i < 3; ++i) {
             ndr->wgId[i] = 0;
             ndr->numWg[i] = divCeil(curTask.gdSize[i], curTask.wgSize[i]);
             ndr->numWgTotal *= ndr->numWg[i];
         }

         ndr->numWgCompleted = 0;
         ndr->globalWgId = 0;
         ndr->wg_disp_rem = true;
         ndr->execDone = false;
         ndr->addrToNotify = (volatile bool*)curTask.addrToNotify;
         ndr->numDispLeft = (volatile uint32_t*)curTask.numDispLeft;
         ndr->dispatchId = nextId;
         ndr->curCid = pkt->req->contextId();
         DPRINTF(GPUDisp, "launching kernel %d\n",nextId);
         execIds.push(nextId);
         ++nextId;

         dispatchActive = true;

         if (!tickEvent.scheduled()) {
             schedule(&tickEvent, curTick() + shader->ticks(1));
         }
     } else {
         // populate current task struct
         // first 64 bits are launch reg
         offset -= 8;
         assert(offset < sizeof(HsaQueueEntry));
         char *curTaskPtr = (char*)&curTask;
         memcpy(curTaskPtr + offset, pkt->getPtr<const void*>(), pkt->getSize());
     }

     pkt->makeAtomicResponse();

     return pioDelay;
 }


 Port &
 GpuDispatcher::getPort(const std::string &if_name, PortID idx)
 {
     if (if_name == "translation_port") {
         return *tlbPort;
     }

     return DmaDevice::getPort(if_name, idx);
 }

 void
 GpuDispatcher::exec()
 {
     int fail_count = 0;

     // There are potentially multiple outstanding kernel launches.
     // It is possible that the workgroups in a different kernel
     // can fit on the GPU even if another kernel's workgroups cannot
     DPRINTF(GPUDisp, "Launching %d Kernels\n", execIds.size());

     while (execIds.size() > fail_count) {
         int execId = execIds.front();

         while (ndRangeMap[execId].wg_disp_rem) {
             //update the thread context
             shader->updateContext(ndRangeMap[execId].curCid);

             // attempt to dispatch_workgroup
             if (!shader->dispatch_workgroups(&ndRangeMap[execId])) {
                 // if we failed try the next kernel,
                 // it may have smaller workgroups.
                 // put it on the queue to rety latter
                 DPRINTF(GPUDisp, "kernel %d failed to launch\n", execId);
                 execIds.push(execId);
                 ++fail_count;
                 break;
             }
         }
         // let's try the next kernel_id
         execIds.pop();
     }

     DPRINTF(GPUDisp, "Returning %d Kernels\n", doneIds.size());

     if (doneIds.size() && cpu) {
         shader->hostWakeUp(cpu);
     }

     while (doneIds.size()) {
         // wakeup the CPU if any Kernels completed this cycle
         DPRINTF(GPUDisp, "WorkGroup %d completed\n", doneIds.front());
         doneIds.pop();
     }
 }

 void
 GpuDispatcher::notifyWgCompl(Wavefront *w)
 {
     int kern_id = w->kernId;
     DPRINTF(GPUDisp, "notify WgCompl %d\n",kern_id);
     assert(ndRangeMap[kern_id].dispatchId == kern_id);
     ndRangeMap[kern_id].numWgCompleted++;

     if (ndRangeMap[kern_id].numWgCompleted == ndRangeMap[kern_id].numWgTotal) {
         ndRangeMap[kern_id].execDone = true;
         doneIds.push(kern_id);

         if (ndRangeMap[kern_id].addrToNotify) {
             accessUserVar(cpu, (uint64_t)(ndRangeMap[kern_id].addrToNotify), 1,
                           0);
         }

         accessUserVar(cpu, (uint64_t)(ndRangeMap[kern_id].numDispLeft), 0, -1);

         // update event end time (in nano-seconds)
         if (ndRangeMap[kern_id].q.depends) {
             HostState *host_state = (HostState*)ndRangeMap[kern_id].q.depends;
             uint64_t event;
             shader->ReadMem((uint64_t)(&host_state->event), &event,
                             sizeof(uint64_t), 0);

             uint64_t end = curTick() / 1000;

             shader->WriteMem((uint64_t)(&((_cl_event*)event)->end), &end,
                              sizeof(uint64_t), 0);
         }
     }

     if (!tickEvent.scheduled()) {
         schedule(&tickEvent, curTick() + shader->ticks(1));
     }
 }

 void
 GpuDispatcher::scheduleDispatch()
 {
     if (!tickEvent.scheduled())
         schedule(&tickEvent, curTick() + shader->ticks(1));
 }

 void
 GpuDispatcher::accessUserVar(BaseCPU *cpu, uint64_t addr, int val, int off)
 {
     if (cpu) {
         if (off) {
             shader->AccessMem(addr, &val, sizeof(int), 0, MemCmd::ReadReq,
                               true);
             val += off;
         }

         shader->AccessMem(addr, &val, sizeof(int), 0, MemCmd::WriteReq, true);
     } else {
         panic("Cannot find host");
     }
 }

 // helper functions for driver to retrieve GPU attributes
 int
 GpuDispatcher::getNumCUs()
 {
     return shader->cuList.size();
 }

 int
 GpuDispatcher::wfSize() const
 {
     return shader->cuList[0]->wfSize();
 }

 void
 GpuDispatcher::setFuncargsSize(int funcargs_size)
 {
     shader->funcargs_size = funcargs_size;
 }

 uint32_t
 GpuDispatcher::getStaticContextSize() const
 {
     return shader->cuList[0]->wfList[0][0]->getStaticContextSize();
 }
	/*
	* Copyright (c) 2011-2015,2018 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: Brad Beckmann,
	* Marc Orr,
	* Anthony Gutierrez
	*/


	#include "gpu-compute/dispatcher.hh"

	#include "cpu/base.hh"
	#include "debug/GPUDisp.hh"
	#include "gpu-compute/cl_driver.hh"
	#include "gpu-compute/cl_event.hh"
	#include "gpu-compute/shader.hh"
	#include "gpu-compute/wavefront.hh"
	#include "mem/packet_access.hh"

	GpuDispatcher *GpuDispatcher::instance = nullptr;

	GpuDispatcher::GpuDispatcher(const Params *p)
	: DmaDevice(p), _masterId(p->system->getMasterId(this, "disp")),
	pioAddr(p->pio_addr), pioSize(4096), pioDelay(p->pio_latency),
	dispatchCount(0), dispatchActive(false), cpu(p->cpu),
	shader(p->shader_pointer), driver(p->cl_driver),
	tickEvent([this]{ exec(); }, "GPU Dispatcher tick",
	false, Event::CPU_Tick_Pri)
	{
	shader->handshake(this);
	driver->handshake(this);

	ndRange.wg_disp_rem = false;
	ndRange.globalWgId = 0;

	schedule(&tickEvent, 0);

	// translation port for the dispatcher
	tlbPort = new TLBPort(csprintf("%s-port%d", name()), this);

	num_kernelLaunched
	.name(name() + ".num_kernel_launched")
	.desc("number of kernel launched")
	;
	}

	GpuDispatcher *GpuDispatcherParams::create()
	{
	GpuDispatcher *dispatcher = new GpuDispatcher(this);
	GpuDispatcher::setInstance(dispatcher);

	return GpuDispatcher::getInstance();
	}

	void
	GpuDispatcher::serialize(CheckpointOut &cp) const
	{
	Tick event_tick = 0;

	if (ndRange.wg_disp_rem)
	fatal("Checkpointing not supported during active workgroup execution");

	if (tickEvent.scheduled())
	event_tick = tickEvent.when();

	SERIALIZE_SCALAR(event_tick);

	}

	void
	GpuDispatcher::unserialize(CheckpointIn &cp)
	{
	Tick event_tick;

	if (tickEvent.scheduled())
	deschedule(&tickEvent);

	UNSERIALIZE_SCALAR(event_tick);

	if (event_tick)
	schedule(&tickEvent, event_tick);
	}

	AddrRangeList
	GpuDispatcher::getAddrRanges() const
	{
	AddrRangeList ranges;

	DPRINTF(GPUDisp, "dispatcher registering addr range at %#x size %#x\n",
	pioAddr, pioSize);

	ranges.push_back(RangeSize(pioAddr, pioSize));

	return ranges;
	}

	Tick
	GpuDispatcher::read(PacketPtr pkt)
	{
	assert(pkt->getAddr() >= pioAddr);
	assert(pkt->getAddr() < pioAddr + pioSize);

	int offset = pkt->getAddr() - pioAddr;
	pkt->allocate();

	DPRINTF(GPUDisp, " read register %#x size=%d\n", offset, pkt->getSize());

	if (offset < 8) {
	assert(!offset);
	assert(pkt->getSize() == 8);

	uint64_t retval = dispatchActive;
	pkt->setLE(retval);
	} else {
	offset -= 8;
	assert(offset + pkt->getSize() < sizeof(HsaQueueEntry));
	char curTaskPtr = (char)&curTask;

	memcpy(pkt->getPtr<const void*>(), curTaskPtr + offset, pkt->getSize());
	}

	pkt->makeAtomicResponse();

	return pioDelay;
	}

	Tick
	GpuDispatcher::write(PacketPtr pkt)
	{
	assert(pkt->getAddr() >= pioAddr);
	assert(pkt->getAddr() < pioAddr + pioSize);

	int offset = pkt->getAddr() - pioAddr;

	#if TRACING_ON
	uint64_t data_val = 0;

	switch (pkt->getSize()) {
	case 1:
	data_val = pkt->getLE<uint8_t>();
	break;
	case 2:
	data_val = pkt->getLE<uint16_t>();
	break;
	case 4:
	data_val = pkt->getLE<uint32_t>();
	break;
	case 8:
	data_val = pkt->getLE<uint64_t>();
	break;
	default:
	DPRINTF(GPUDisp, "bad size %d\n", pkt->getSize());
	}

	DPRINTF(GPUDisp, "write register %#x value %#x size=%d\n", offset, data_val,
	pkt->getSize());
	#endif
	if (!offset) {
	static int nextId = 0;

	// The depends field of the qstruct, which was previously unused, is
	// used to communicate with simulated application.
	if (curTask.depends) {
	HostState hs;
	shader->ReadMem((uint64_t)(curTask.depends), &hs,
	sizeof(HostState), 0);

	// update event start time (in nano-seconds)
	uint64_t start = curTick() / 1000;

	shader->WriteMem((uint64_t)(&((_cl_event*)hs.event)->start),
	&start, sizeof(uint64_t), 0);
	}

	// launch kernel
	++num_kernelLaunched;

	NDRange *ndr = &(ndRangeMap[nextId]);
	// copy dispatch info
	ndr->q = curTask;

	// update the numDispTask polled by the runtime
	accessUserVar(cpu, (uint64_t)(curTask.numDispLeft), 0, 1);

	ndr->numWgTotal = 1;

	for (int i = 0; i < 3; ++i) {
	ndr->wgId[i] = 0;
	ndr->numWg[i] = divCeil(curTask.gdSize[i], curTask.wgSize[i]);
	ndr->numWgTotal *= ndr->numWg[i];
	}

	ndr->numWgCompleted = 0;
	ndr->globalWgId = 0;
	ndr->wg_disp_rem = true;
	ndr->execDone = false;
	ndr->addrToNotify = (volatile bool*)curTask.addrToNotify;
	ndr->numDispLeft = (volatile uint32_t*)curTask.numDispLeft;
	ndr->dispatchId = nextId;
	ndr->curCid = pkt->req->contextId();
	DPRINTF(GPUDisp, "launching kernel %d\n",nextId);
	execIds.push(nextId);
	++nextId;

	dispatchActive = true;

	if (!tickEvent.scheduled()) {
	schedule(&tickEvent, curTick() + shader->ticks(1));
	}
	} else {
	// populate current task struct
	// first 64 bits are launch reg
	offset -= 8;
	assert(offset < sizeof(HsaQueueEntry));
	char curTaskPtr = (char)&curTask;
	memcpy(curTaskPtr + offset, pkt->getPtr<const void*>(), pkt->getSize());
	}

	pkt->makeAtomicResponse();

	return pioDelay;
	}


	Port &
	GpuDispatcher::getPort(const std::string &if_name, PortID idx)
	{
	if (if_name == "translation_port") {
	return *tlbPort;
	}

	return DmaDevice::getPort(if_name, idx);
	}

	void
	GpuDispatcher::exec()
	{
	int fail_count = 0;

	// There are potentially multiple outstanding kernel launches.
	// It is possible that the workgroups in a different kernel
	// can fit on the GPU even if another kernel's workgroups cannot
	DPRINTF(GPUDisp, "Launching %d Kernels\n", execIds.size());

	while (execIds.size() > fail_count) {
	int execId = execIds.front();

	while (ndRangeMap[execId].wg_disp_rem) {
	//update the thread context
	shader->updateContext(ndRangeMap[execId].curCid);

	// attempt to dispatch_workgroup
	if (!shader->dispatch_workgroups(&ndRangeMap[execId])) {
	// if we failed try the next kernel,
	// it may have smaller workgroups.
	// put it on the queue to rety latter
	DPRINTF(GPUDisp, "kernel %d failed to launch\n", execId);
	execIds.push(execId);
	++fail_count;
	break;
	}
	}
	// let's try the next kernel_id
	execIds.pop();
	}

	DPRINTF(GPUDisp, "Returning %d Kernels\n", doneIds.size());

	if (doneIds.size() && cpu) {
	shader->hostWakeUp(cpu);
	}

	while (doneIds.size()) {
	// wakeup the CPU if any Kernels completed this cycle
	DPRINTF(GPUDisp, "WorkGroup %d completed\n", doneIds.front());
	doneIds.pop();
	}
	}

	void
	GpuDispatcher::notifyWgCompl(Wavefront *w)
	{
	int kern_id = w->kernId;
	DPRINTF(GPUDisp, "notify WgCompl %d\n",kern_id);
	assert(ndRangeMap[kern_id].dispatchId == kern_id);
	ndRangeMap[kern_id].numWgCompleted++;

	if (ndRangeMap[kern_id].numWgCompleted == ndRangeMap[kern_id].numWgTotal) {
	ndRangeMap[kern_id].execDone = true;
	doneIds.push(kern_id);

	if (ndRangeMap[kern_id].addrToNotify) {
	accessUserVar(cpu, (uint64_t)(ndRangeMap[kern_id].addrToNotify), 1,
	0);
	}

	accessUserVar(cpu, (uint64_t)(ndRangeMap[kern_id].numDispLeft), 0, -1);

	// update event end time (in nano-seconds)
	if (ndRangeMap[kern_id].q.depends) {
	HostState host_state = (HostState)ndRangeMap[kern_id].q.depends;
	uint64_t event;
	shader->ReadMem((uint64_t)(&host_state->event), &event,
	sizeof(uint64_t), 0);

	uint64_t end = curTick() / 1000;

	shader->WriteMem((uint64_t)(&((_cl_event*)event)->end), &end,
	sizeof(uint64_t), 0);
	}
	}

	if (!tickEvent.scheduled()) {
	schedule(&tickEvent, curTick() + shader->ticks(1));
	}
	}

	void
	GpuDispatcher::scheduleDispatch()
	{
	if (!tickEvent.scheduled())
	schedule(&tickEvent, curTick() + shader->ticks(1));
	}

	void
	GpuDispatcher::accessUserVar(BaseCPU *cpu, uint64_t addr, int val, int off)
	{
	if (cpu) {
	if (off) {
	shader->AccessMem(addr, &val, sizeof(int), 0, MemCmd::ReadReq,
	true);
	val += off;
	}

	shader->AccessMem(addr, &val, sizeof(int), 0, MemCmd::WriteReq, true);
	} else {
	panic("Cannot find host");
	}
	}

	// helper functions for driver to retrieve GPU attributes
	int
	GpuDispatcher::getNumCUs()
	{
	return shader->cuList.size();
	}

	int
	GpuDispatcher::wfSize() const
	{
	return shader->cuList[0]->wfSize();
	}

	void
	GpuDispatcher::setFuncargsSize(int funcargs_size)
	{
	shader->funcargs_size = funcargs_size;
	}

	uint32_t
	GpuDispatcher::getStaticContextSize() const
	{
	return shader->cuList[0]->wfList[0][0]->getStaticContextSize();
	}