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[Bug nptl/4274] Performance issue: pthread_cond_signal() causes three context switches instead of one
- From: "triegel at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Wed, 11 Jan 2017 17:42:32 +0000
- Subject: [Bug nptl/4274] Performance issue: pthread_cond_signal() causes three context switches instead of one
- Auto-submitted: auto-generated
- References: <bug-4274-131@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=4274
Torvald Riegel <triegel at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
CC| |triegel at redhat dot com
Resolution|--- |OBSOLETE
--- Comment #13 from Torvald Riegel <triegel at redhat dot com> ---
A new condition variable implementation has been committed, which as different
performance properties.
The statements made in comment #9 do not really consider what is actually going
on (e.g., waking another thread does not generally require the kernel to
context switch to it immediately; not being able to acquire a mutex does not
mean the respective thread has to block using futexes right away; the scenario
plays out differently on a multiprocessor that is not oversubscribed; ...).
The new condition variable implementation contains code comments that discuss
related aspects in some more detail.
Therefore, I'm closing this bug. If you observe a potential performance
problem with the new condition variable, please open a new bug.
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