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[Bug nptl/4274] Performance issue: pthread_cond_signal() causes three context switches instead of one
- From: "drepper at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 25 Aug 2007 05:38:58 -0000
- Subject: [Bug nptl/4274] Performance issue: pthread_cond_signal() causes three context switches instead of one
- References: <20070325101629.4274.bart.vanassche@gmail.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From drepper at redhat dot com 2007-08-25 05:38 -------
Whatever you think you are measuring has nothing to do with glibc. Should there
actually be extra wake-ups this happens entirely in the kernel. glibc uses
FUTEX_WAKE_OP which prevents unnecessary delays. If the kernel schedules
freshly woken threads right away before finishing the futex call something of
course can go wrong. But all this happens in the kernel. glibc gives the
kernel all the information it needs to avoid any problem.
Talk to the kernel people.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
http://sourceware.org/bugzilla/show_bug.cgi?id=4274
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