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Reduce lock contention in __tz_convert() [BZ #16145] (partial fix) 

This patch is an "easy win" partial fix for BZ #16145, which notes
the heavy contention on tzset_lock when multiple threads are converting
times with localtime_r().

In __tz_convert(), the lock does not need to be held after
__tzfile_compute() / __tz_compute() have been called, so we can move the
unlock up.  At this point there is still significant work to be done in
__offtime(), so we see some improvement (in my testing with 8 cores
banging on localtime_r(), ~20% improvement in throughput).
This commit is contained in:
Kevin Easton 2015-02-24 23:57:07 -05:00 committed by Mike Frysinger
parent b433df00ae
commit 6807b1db82
2 changed files with 8 additions and 2 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2015-02-24 Kevin Easton <kevin@guarana.org>
[BZ #16145] (partial fix)
* time/tzset.c (__tz_convert): Unlock tzset_lock earlier
to reduce lock contention.
2015-02-24 Miroslav Lichvar <mlichvar@redhat.com>
* sysdeps/unix/sysv/linux/bits/timex.h: Update version.

4
time/tzset.c
View File

@ -644,6 +644,8 @@ __tz_convert (const time_t *timer, int use_localtime, struct tm *tp)
leap_extra_secs = 0;
}
__libc_lock_unlock (tzset_lock);
if (tp)
{
if (! use_localtime)
@ -659,8 +661,6 @@ __tz_convert (const time_t *timer, int use_localtime, struct tm *tp)
tp = NULL;
}
__libc_lock_unlock (tzset_lock);
return tp;
}