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JobSystem: remove the DONT_SIGNAL flag

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A side effect of this flag was that we had to always use notify_all
when starting a job, instead of notify_one -- in practice, we found
experimentally that more calls to notify_one is cheaper than fewer
calls to notify_all.
This commit is contained in:
Mathias Agopian
2021-06-04 13:57:57 -07:00
committed by Mathias Agopian
parent c5ef1d6252
commit bbc4f4f21d
7 changed files with 35 additions and 34 deletions
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31
libs/utils/src/JobSystem.cpp
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@@ -247,13 +247,22 @@ void JobSystem::wait(std::unique_lock<Mutex>& lock, Job* job) noexcept {
}
}
void JobSystem::wake() noexcept {
void JobSystem::wakeAll() noexcept {
HEAVY_SYSTRACE_CALL();
std::lock_guard<Mutex> lock(mWaiterLock);
// this empty critical section is needed -- it guarantees that notifiy_all() happens
// after the condition variables are set.
// this empty critical section is needed -- it guarantees that notify_all() happens
// after the condition's variables are set.
mWaiterCondition.notify_all();
}
void JobSystem::wakeOne() noexcept {
HEAVY_SYSTRACE_CALL();
std::lock_guard<Mutex> lock(mWaiterLock);
// this empty critical section is needed -- it guarantees that notify_one() happens
// after the condition's variables are set.
mWaiterCondition.notify_one();
}
inline JobSystem::ThreadState& JobSystem::getState() noexcept {
std::lock_guard<utils::SpinLock> lock(mThreadMapLock);
auto iter = mThreadMap.find(std::this_thread::get_id());
@@ -380,7 +389,7 @@ void JobSystem::finish(Job* job) noexcept {
// wake-up all threads that could potentially be waiting on this job finishing
if (notify) {
wake();
wakeAll();
}
}
@@ -428,10 +437,10 @@ void JobSystem::release(JobSystem::Job*& job) noexcept {
}
void JobSystem::signal() noexcept {
wake();
wakeAll();
}
void JobSystem::run(JobSystem::Job*& job, uint32_t flags) noexcept {
void JobSystem::run(Job*& job) noexcept {
HEAVY_SYSTRACE_CALL();
ThreadState& state(getState());
@@ -446,19 +455,15 @@ void JobSystem::run(JobSystem::Job*& job, uint32_t flags) noexcept {
HEAVY_SYSTRACE_VALUE32("JobSystem::activeJobs", activeJobs + 1);
// wake-up a thread if needed...
if (!(flags & DONT_SIGNAL)) {
// wake-up multiple queues because there could be multiple jobs queued
// especially if DONT_SIGNAL was used
wake();
}
wakeOne();
// after run() returns, the job is virtually invalid (it'll die on its own)
job = nullptr;
}
JobSystem::Job* JobSystem::runAndRetain(JobSystem::Job* job, uint32_t flags) noexcept {
JobSystem::Job* JobSystem::runAndRetain(Job* job) noexcept {
JobSystem::Job* retained = retain(job);
run(job, flags);
run(job);
return retained;
}