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authorIngo Molnar <mingo@elte.hu>2007-07-15 23:41:18 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:48 -0700
commit4e44f3497d41db4c3b9051c61410dee8ae4fb49c (patch)
tree8c54919894c8f6ac629c6c28cee8fb504721d652 /include/linux/cdrom.h
parentf482394ccbca7234d29cc146d4a2b94f976ce5a1 (diff)
sys_time() speedup
Improve performance of sys_time(). sys_time() returns time in seconds, but it does so by calling do_gettimeofday() and then returning the tv_sec portion of the GTOD time. But the data structure "xtime", which is updated by every timer/scheduler tick, already offers HZ granularity time. The patch improves the sysbench OLTP macrobenchmark significantly: 2.6.22-rc6: #threads 1: transactions: 3733 (373.21 per sec.) 2: transactions: 6676 (667.46 per sec.) 3: transactions: 6957 (695.50 per sec.) 4: transactions: 7055 (705.48 per sec.) 5: transactions: 6596 (659.33 per sec.) 2.6.22-rc6 + sys_time.patch: 1: transactions: 4005 (400.47 per sec.) 2: transactions: 7379 (737.77 per sec.) 3: transactions: 7347 (734.49 per sec.) 4: transactions: 7468 (746.65 per sec.) 5: transactions: 7428 (742.47 per sec.) Mixed API uses of gettimeofday() and time() are guaranteed to be coherent via the use of a at-most-once-per-second slowpath that updates xtime. [akpm@linux-foundation.org: build fixes] Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/cdrom.h')
0 files changed, 0 insertions, 0 deletions