dispatcher.cc

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/*
 * Copyright (c) 2011-2015,2018 Advanced Micro Devices, Inc.
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 * modification, are permitted provided that the following conditions are met:
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 * this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
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 * software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include "gpu-compute/dispatcher.hh"
 
#include "debug/GPUAgentDisp.hh"
#include "debug/GPUDisp.hh"
#include "debug/GPUKernelInfo.hh"
#include "debug/GPUWgLatency.hh"
#include "gpu-compute/gpu_command_processor.hh"
#include "gpu-compute/hsa_queue_entry.hh"
#include "gpu-compute/shader.hh"
#include "gpu-compute/wavefront.hh"
#include "sim/sim_exit.hh"
#include "sim/syscall_emul_buf.hh"
#include "sim/system.hh"
 
namespace gem5
{
 
GPUDispatcher::GPUDispatcher(const Params &p)
    : SimObject(p), shader(nullptr), gpuCmdProc(nullptr),
      tickEvent([this]{ exec(); },
          "GPU Dispatcher tick", false, Event::CPU_Tick_Pri),
      dispatchActive(false), kernelExitEvents(p.kernel_exit_events),
      stats(this)
{
    schedule(&tickEvent, 0);
}
 
GPUDispatcher::~GPUDispatcher()
{
}
 
HSAQueueEntry*
GPUDispatcher::hsaTask(int disp_id)
{
    assert(hsaQueueEntries.find(disp_id) != hsaQueueEntries.end());
    return hsaQueueEntries[disp_id];
}
 
void
GPUDispatcher::setCommandProcessor(GPUCommandProcessor *gpu_cmd_proc)
{
    gpuCmdProc = gpu_cmd_proc;
}
 
void
GPUDispatcher::setShader(Shader *new_shader)
{
    shader = new_shader;
}
 
void
GPUDispatcher::serialize(CheckpointOut &cp) const
{
    Tick event_tick = 0;
 
    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);
    }
}

void
GPUDispatcher::dispatch(HSAQueueEntry *task)
{
    ++stats.numKernelLaunched;
 
    DPRINTF(GPUDisp, "launching kernel: %s, dispatch ID: %d\n",
            task->kernelName(), task->dispatchId());
    DPRINTF(GPUAgentDisp, "launching kernel: %s, dispatch ID: %d\n",
            task->kernelName(), task->dispatchId());
 
    execIds.push(task->dispatchId());
    dispatchActive = true;
    hsaQueueEntries.emplace(task->dispatchId(), task);
 
    if (!tickEvent.scheduled()) {
        schedule(&tickEvent, curTick() + shader->clockPeriod());
    }
}
 
void
GPUDispatcher::exec()
{
    int fail_count(0);
    int disp_count(0);

    DPRINTF(GPUDisp, "Launching %d Kernels\n", execIds.size());
    DPRINTF(GPUAgentDisp, "Launching %d Kernels\n", execIds.size());
 
    if (execIds.size() > 0) {
        ++stats.cyclesWaitingForDispatch;
    }

    while (execIds.size() > fail_count) {
        int exec_id = execIds.front();
        auto task = hsaQueueEntries[exec_id];
        bool launched(false);
 
        // acq is needed before starting dispatch
        if (shader->impl_kern_launch_acq) {
            // try to invalidate cache
            shader->prepareInvalidate(task);
        } else {
            // kern launch acquire is not set, skip invalidate
            task->markInvDone();
        }

        if (!task->isInvDone()){
            execIds.push(exec_id);
            ++fail_count;
 
            DPRINTF(GPUDisp, "kernel %d failed to launch, due to [%d] pending"
                " invalidate requests\n", exec_id, task->outstandingInvs());
 
            // try the next kernel_id
            execIds.pop();
            continue;
        }
 
        // kernel invalidate is done, start workgroup dispatch
        while (!task->dispComplete()) {
            // update the thread context
            shader->updateContext(task->contextId());
 
            // attempt to dispatch workgroup
            DPRINTF(GPUWgLatency, "Attempt Kernel Launch cycle:%d kernel:%d\n",
                curTick(), exec_id);
 
            if (!shader->dispatchWorkgroups(task)) {
                DPRINTF(GPUDisp, "kernel %d failed to launch\n", exec_id);
                execIds.push(exec_id);
                ++fail_count;
                break;
            } else if (!launched) {
                launched = true;
                disp_count++;
                DPRINTF(GPUKernelInfo, "Launched kernel %d for WG %d\n",
                            exec_id, disp_count);
            }
        }
 
        // try the next kernel_id
        execIds.pop();
    }
 
    DPRINTF(GPUDisp, "Returning %d Kernels\n", doneIds.size());
    DPRINTF(GPUWgLatency, "Kernel Wgs dispatched: %d | %d failures\n",
            disp_count, fail_count);
 
    while (doneIds.size()) {
        DPRINTF(GPUDisp, "Kernel %d completed\n", doneIds.front());
        doneIds.pop();
    }
}
 
bool
GPUDispatcher::isReachingKernelEnd(Wavefront *wf)
{
    int kern_id = wf->kernId;
    assert(hsaQueueEntries.find(kern_id) != hsaQueueEntries.end());
    auto task = hsaQueueEntries[kern_id];
    assert(task->dispatchId() == kern_id);

    return (task->numWgCompleted() + 1 == task->numWgTotal());
}

void
GPUDispatcher::updateInvCounter(int kern_id, int val) {
    assert(val == -1 || val == 1);
 
    auto task = hsaQueueEntries[kern_id];
    task->updateOutstandingInvs(val);
 
    // kernel invalidate is done, schedule dispatch work
    if (task->isInvDone() && !tickEvent.scheduled()) {
        schedule(&tickEvent, curTick() + shader->clockPeriod());
    }
}

bool
GPUDispatcher::updateWbCounter(int kern_id, int val) {
    assert(val == -1 || val == 1);
 
    auto task = hsaQueueEntries[kern_id];
    task->updateOutstandingWbs(val);
 
    // true: WB is done, false: WB is still ongoing
    return (task->outstandingWbs() == 0);
}

int
GPUDispatcher::getOutstandingWbs(int kernId) {
    auto task = hsaQueueEntries[kernId];
 
    return task->outstandingWbs();
}

void
GPUDispatcher::notifyWgCompl(Wavefront *wf)
{
    int kern_id = wf->kernId;
    DPRINTF(GPUDisp, "notify WgCompl %d\n", wf->wgId);
    auto task = hsaQueueEntries[kern_id];
    assert(task->dispatchId() == kern_id);
    task->notifyWgCompleted();
 
    DPRINTF(GPUWgLatency, "WG Complete cycle:%d wg:%d kernel:%d cu:%d\n",
        curTick(), wf->wgId, kern_id, wf->computeUnit->cu_id);
 
    if (task->numWgCompleted() == task->numWgTotal()) {
        // Notify the HSA PP that this kernel is complete
        gpuCmdProc->hsaPacketProc()
            .finishPkt(task->dispPktPtr(), task->queueId());
        if (task->completionSignal()) {
            DPRINTF(GPUDisp, "HSA AQL Kernel Complete with completion "
                    "signal! Addr: %d\n", task->completionSignal());
 
            gpuCmdProc->sendCompletionSignal(task->completionSignal());
        } else {
            DPRINTF(GPUDisp, "HSA AQL Kernel Complete! No completion "
                "signal\n");
        }
 
        DPRINTF(GPUWgLatency, "Kernel Complete ticks:%d kernel:%d\n",
                curTick(), kern_id);
        DPRINTF(GPUKernelInfo, "Completed kernel %d\n", kern_id);
 
        if (kernelExitEvents) {
            shader->requestKernelExitEvent(task->completionSignal());
        }
    }
 
    if (!tickEvent.scheduled()) {
        schedule(&tickEvent, curTick() + shader->clockPeriod());
    }
}
 
void
GPUDispatcher::scheduleDispatch()
{
    if (!tickEvent.scheduled()) {
        schedule(&tickEvent, curTick() + shader->clockPeriod());
    }
}
 
GPUDispatcher::GPUDispatcherStats::GPUDispatcherStats(
    statistics::Group *parent)
    : statistics::Group(parent),
      ADD_STAT(numKernelLaunched, "number of kernel launched"),
      ADD_STAT(cyclesWaitingForDispatch, "number of cycles with outstanding "
               "wavefronts that are waiting to be dispatched")
{
}
 
} // namespace gem5