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v8: don't busy loop in cpu profiler thread #8789
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Reduce the overhead of the CPU profiler by replacing sched_yield() with nanosleep() in V8's tick event processor thread. The former only yields the CPU when there is another process scheduled on the same CPU. Before this commit, the thread would effectively busy loop and consume 100% CPU time. By forcing a one nanosecond sleep period rounded up to the task scheduler's granularity (about 50 us on Linux), CPU usage for the processor thread now hovers around 10-20% for a busy application. Refs strongloop/strong-agent#3 and strongloop-internal/scrum-cs#37.
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@bnoordhuis Is this a change that will be upstream'd? Either way, nice change. After you ping back I'll land this. |
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I don't think there is anything I can upstream. 3.14 is dead upstream and newer V8 versions don't seem to have this issue (or at least, I haven't seen it myself and none of our customers have complained about it so far.) |
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Wow, that's quite a substantial improvement. Great job! |
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@trevnorris Ping. |
trevnorris
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Jan 13, 2015
Reduce the overhead of the CPU profiler by replacing sched_yield() with nanosleep() in V8's tick event processor thread. The former only yields the CPU when there is another process scheduled on the same CPU. Before this commit, the thread would effectively busy loop and consume 100% CPU time. By forcing a one nanosecond sleep period rounded up to the task scheduler's granularity (about 50 us on Linux), CPU usage for the processor thread now hovers around 10-20% for a busy application. PR-URL: #8789 Ref: strongloop/strong-agent#3 Reviewed-by: Trevor Norris <trev.norris@gmail.com>
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@bnoordhuis Thanks for the ping. Landed in 6ebd85e. |
tunniclm
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May 8, 2015
Backport 6964a9e0685fa186d9d9b7907be17505e839db1a from upstream v8. Original commit message: Make CPU profiler do not hog 100% of CPU. Tick event processor should not stay in a tight loop when there's nothing to do. It can go sleep until next sample event. LOG=N BUG=v8:3967 Committed: https://crrev.com/6964a9e0685fa186d9d9b7907be17505e839db1a Cr-Commit-Position: refs/heads/master@{#28211} Fixes nodejs#25137 Related: nodejs#9439, nodejs#8789
misterdjules
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May 12, 2015
Backport 6964a9e0685fa186d9d9b7907be17505e839db1a from upstream v8. Original commit message: Make CPU profiler do not hog 100% of CPU. Tick event processor should not stay in a tight loop when there's nothing to do. It can go sleep until next sample event. LOG=N BUG=v8:3967 Committed: https://crrev.com/6964a9e0685fa186d9d9b7907be17505e839db1a Cr-Commit-Position: refs/heads/master@{#28211} Fixes nodejs#25137 Related: nodejs#9439, nodejs#8789 PR: nodejs#25268 PR-URL: nodejs#25268 Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com> Reviewed-By: Julien Gilli <jgilli@fastmail.fm>
jeroen
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Jun 30, 2016
Reduce the overhead of the CPU profiler by replacing sched_yield() with nanosleep() in V8's tick event processor thread. The former only yields the CPU when there is another process scheduled on the same CPU. Before this commit, the thread would effectively busy loop and consume 100% CPU time. By forcing a one nanosecond sleep period rounded up to the task scheduler's granularity (about 50 us on Linux), CPU usage for the processor thread now hovers around 10-20% for a busy application. PR-URL: nodejs/node-v0.x-archive#8789 Ref: strongloop/strong-agent#3 Reviewed-by: Trevor Norris <trev.norris@gmail.com> Signed-off-by: Jeroen Ooms <jeroenooms@gmail.com>
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Reduce the overhead of the CPU profiler by replacing sched_yield() with
nanosleep() in V8's tick event processor thread. The former only yields
the CPU when there is another process scheduled on the same CPU.
Before this commit, the thread would effectively busy loop and consume
100% CPU time. By forcing a one nanosecond sleep period rounded up to
the task scheduler's granularity (about 50 us on Linux), CPU usage for
the processor thread now hovers around 10-20% for a busy application.
Refs strongloop/strong-agent#3 and strongloop-internal/scrum-cs#37.
R=@trevnorris?