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// -*- mode: C++; c-file-style: "cc-mode" -*-
//=============================================================================
//
// Copyright 2012-2020 by Wilson Snyder. This program is free software; you can
// redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
//=============================================================================
///
/// \file
/// \brief Thread pool for verilated modules
///
//=============================================================================
#include "verilatedos.h"
#include "verilated_threads.h"
#include <cstdio>
std::atomic<vluint64_t> VlMTaskVertex::s_yields;
VL_THREAD_LOCAL VlThreadPool::ProfileTrace* VlThreadPool::t_profilep = NULL;
//=============================================================================
// VlMTaskVertex
VlMTaskVertex::VlMTaskVertex(vluint32_t upstreamDepCount)
: m_upstreamDepsDone(0)
, m_upstreamDepCount(upstreamDepCount) {
assert(atomic_is_lock_free(&m_upstreamDepsDone));
}
//=============================================================================
// VlWorkerThread
VlWorkerThread::VlWorkerThread(VlThreadPool* poolp, bool profiling)
: m_waiting(false)
, m_ready_size(0)
, m_poolp(poolp)
, m_profiling(profiling)
, m_exiting(false)
// Must init this last -- after setting up fields that it might read:
, m_cthread(startWorker, this) {}
VlWorkerThread::~VlWorkerThread() {
m_exiting.store(true, std::memory_order_release);
wakeUp();
// The thread should exit; join it.
m_cthread.join();
}
void VlWorkerThread::workerLoop() {
if (VL_UNLIKELY(m_profiling)) m_poolp->setupProfilingClientThread();
ExecRec work;
work.m_fnp = NULL;
while (true) {
if (VL_LIKELY(!work.m_fnp)) dequeWork(&work);
// Do this here, not above, to avoid a race with the destructor.
if (VL_UNLIKELY(m_exiting.load(std::memory_order_acquire))) break;
if (VL_LIKELY(work.m_fnp)) {
work.m_fnp(work.m_evenCycle, work.m_sym);
work.m_fnp = NULL;
}
}
if (VL_UNLIKELY(m_profiling)) m_poolp->tearDownProfilingClientThread();
}
void VlWorkerThread::startWorker(VlWorkerThread* workerp) { workerp->workerLoop(); }
//=============================================================================
// VlThreadPool
VlThreadPool::VlThreadPool(int nThreads, bool profiling)
: m_profiling(profiling) {
// --threads N passes nThreads=N-1, as the "main" threads counts as 1
unsigned cpus = std::thread::hardware_concurrency();
if (cpus < nThreads + 1) {
static int warnedOnce = 0;
if (!warnedOnce++) {
VL_PRINTF_MT("%%Warning: System has %u CPUs but model Verilated with"
" --threads %d; may run slow.\n",
cpus, nThreads + 1);
}
}
// Create'em
for (int i = 0; i < nThreads; ++i) {
m_workers.push_back(new VlWorkerThread(this, profiling));
}
// Set up a profile buffer for the current thread too -- on the
// assumption that it's the same thread that calls eval and may be
// donated to run mtasks during the eval.
if (VL_UNLIKELY(m_profiling)) setupProfilingClientThread();
}
VlThreadPool::~VlThreadPool() {
for (int i = 0; i < m_workers.size(); ++i) {
// Each ~WorkerThread will wait for its thread to exit.
delete m_workers[i];
}
if (VL_UNLIKELY(m_profiling)) tearDownProfilingClientThread();
}
void VlThreadPool::tearDownProfilingClientThread() {
assert(t_profilep);
delete t_profilep;
t_profilep = NULL;
}
void VlThreadPool::setupProfilingClientThread() {
assert(!t_profilep);
t_profilep = new ProfileTrace;
// Reserve some space in the thread-local profiling buffer;
// try not to malloc while collecting profiling.
t_profilep->reserve(4096);
{
const VerilatedLockGuard lk(m_mutex);
m_allProfiles.insert(t_profilep);
}
}
void VlThreadPool::profileAppendAll(const VlProfileRec& rec) {
const VerilatedLockGuard lk(m_mutex);
for (ProfileSet::iterator it = m_allProfiles.begin(); it != m_allProfiles.end(); ++it) {
// Every thread's profile trace gets a copy of rec.
(*it)->emplace_back(rec);
}
}
void VlThreadPool::profileDump(const char* filenamep, vluint64_t ticksElapsed) {
const VerilatedLockGuard lk(m_mutex);
VL_DEBUG_IF(VL_DBG_MSGF("+prof+threads writing to '%s'\n", filenamep););
FILE* fp = fopen(filenamep, "w");
if (VL_UNLIKELY(!fp)) {
VL_FATAL_MT(filenamep, 0, "", "+prof+threads+file file not writable");
// cppcheck-suppress resourceLeak // bug, doesn't realize fp is nullptr
return;
}
// TODO Perhaps merge with verilated_coverage output format, so can
// have a common merging and reporting tool, etc.
fprintf(fp, "VLPROFTHREAD 1.0 # Verilator thread profile dump version 1.0\n");
fprintf(fp, "VLPROF arg --threads %" VL_PRI64 "u\n", vluint64_t(m_workers.size() + 1));
fprintf(fp, "VLPROF arg +verilator+prof+threads+start+%" VL_PRI64 "u\n",
Verilated::profThreadsStart());
fprintf(fp, "VLPROF arg +verilator+prof+threads+window+%u\n", Verilated::profThreadsWindow());
fprintf(fp, "VLPROF stat yields %" VL_PRI64 "u\n", VlMTaskVertex::yields());
vluint32_t thread_id = 0;
for (ProfileSet::const_iterator pit = m_allProfiles.begin(); pit != m_allProfiles.end();
++pit) {
++thread_id;
bool printing = false; // False while in warmup phase
for (ProfileTrace::const_iterator eit = (*pit)->begin(); eit != (*pit)->end(); ++eit) {
switch (eit->m_type) {
case VlProfileRec::TYPE_BARRIER: //
printing = true;
break;
case VlProfileRec::TYPE_MTASK_RUN:
if (!printing) break;
fprintf(fp,
"VLPROF mtask %d"
" start %" VL_PRI64 "u end %" VL_PRI64 "u elapsed %" VL_PRI64 "u"
" predict_time %u cpu %u on thread %u\n",
eit->m_mtaskId, eit->m_startTime, eit->m_endTime,
(eit->m_endTime - eit->m_startTime), eit->m_predictTime, eit->m_cpu,
thread_id);
break;
default: assert(false); break; // LCOV_EXCL_LINE
}
}
}
fprintf(fp, "VLPROF stat ticks %" VL_PRI64 "u\n", ticksElapsed);
fclose(fp);
}
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