diff options
| author | Ingo Molnar <mingo@elte.hu> | 2007-10-16 18:09:20 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 21:01:50 +0400 |
| commit | f20bf6125605acbbc7eb8c9420d7221c91aa83eb (patch) | |
| tree | ce3dd753431dd32b346aa19f2f7b6bb84bb1f22e /kernel/time.c | |
| parent | 8636225e8d23e6079d43f56faf415bd71b589dc0 (diff) | |
| download | linux-f20bf6125605acbbc7eb8c9420d7221c91aa83eb.tar.xz | |
time: introduce xtime_seconds
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 by 4-5% on an AMD
dual-core system:
v2.6.23:
#threads
1: transactions: 4073 (407.23 per sec.)
2: transactions: 8530 (852.81 per sec.)
3: transactions: 8321 (831.88 per sec.)
4: transactions: 8407 (840.58 per sec.)
5: transactions: 8070 (806.74 per sec.)
v2.6.23 + sys_time-speedup.patch:
1: transactions: 4281 (428.09 per sec.)
2: transactions: 8910 (890.85 per sec.)
3: transactions: 8659 (865.79 per sec.)
4: transactions: 8676 (867.34 per sec.)
5: transactions: 8532 (852.91 per sec.)
and by 4-5% on an Intel dual-core system too:
2.6.23:
1: transactions: 4560 (455.94 per sec.)
2: transactions: 10094 (1009.30 per sec.)
3: transactions: 9755 (975.36 per sec.)
4: transactions: 9859 (985.78 per sec.)
5: transactions: 9701 (969.72 per sec.)
2.6.23 + sys_time-speedup.patch:
1: transactions: 4779 (477.84 per sec.)
2: transactions: 10103 (1010.14 per sec.)
3: transactions: 10141 (1013.93 per sec.)
4: transactions: 10371 (1036.89 per sec.)
5: transactions: 10178 (1017.50 per sec.)
(the more CPUs the system has, the more speedup this patch gives for
this particular workload.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/time.c')
| -rw-r--r-- | kernel/time.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/time.c b/kernel/time.c index 2289a8d68314..1afcc78dc3b1 100644 --- a/kernel/time.c +++ b/kernel/time.c @@ -57,11 +57,7 @@ EXPORT_SYMBOL(sys_tz); */ asmlinkage long sys_time(time_t __user * tloc) { - time_t i; - struct timespec tv; - - getnstimeofday(&tv); - i = tv.tv_sec; + time_t i = get_seconds(); if (tloc) { if (put_user(i,tloc)) |