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| author | Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> | 2009-11-26 14:48:30 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-26 12:59:19 +0100 |
| commit | d180c5bccec02612256fd8076ff3c1fac3429553 (patch) | |
| tree | 1ef4a45c81531645640380965916c68bbe7f6abb /kernel/sys.c | |
| parent | 16bc67edeb49b531940b2ba6c183780a1b5c472d (diff) | |
| download | lwn-d180c5bccec02612256fd8076ff3c1fac3429553.tar.gz lwn-d180c5bccec02612256fd8076ff3c1fac3429553.zip | |
sched: Introduce task_times() to replace task_{u,s}time() pair
Functions task_{u,s}time() are called in pair in almost all
cases. However task_stime() is implemented to call task_utime()
from its inside, so such paired calls run task_utime() twice.
It means we do heavy divisions (div_u64 + do_div) twice to get
utime and stime which can be obtained at same time by one set
of divisions.
This patch introduces a function task_times(*tsk, *utime,
*stime) to retrieve utime and stime at once in better, optimized
way.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16AE.906@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sys.c')
| -rw-r--r-- | kernel/sys.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index ce17760d9c51..bbdfce0d4347 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1346,8 +1346,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r) utime = stime = cputime_zero; if (who == RUSAGE_THREAD) { - utime = task_utime(current); - stime = task_stime(current); + task_times(current, &utime, &stime); accumulate_thread_rusage(p, r); maxrss = p->signal->maxrss; goto out; |