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authorHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>2009-11-26 06:48:30 +0100
committerIngo Molnar <mingo@elte.hu>2009-11-26 12:59:19 +0100
commitd180c5bccec02612256fd8076ff3c1fac3429553 (patch)
tree1ef4a45c81531645640380965916c68bbe7f6abb /kernel/exit.c
parentMerge branch 'sched/urgent' into sched/core (diff)
downloadlinux-d180c5bccec02612256fd8076ff3c1fac3429553.tar.xz
linux-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/exit.c')
-rw-r--r--kernel/exit.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index f7864ac2ecc1..29068ab2670a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -91,6 +91,8 @@ static void __exit_signal(struct task_struct *tsk)
if (atomic_dec_and_test(&sig->count))
posix_cpu_timers_exit_group(tsk);
else {
+ cputime_t utime, stime;
+
/*
* If there is any task waiting for the group exit
* then notify it:
@@ -110,8 +112,9 @@ static void __exit_signal(struct task_struct *tsk)
* We won't ever get here for the group leader, since it
* will have been the last reference on the signal_struct.
*/
- sig->utime = cputime_add(sig->utime, task_utime(tsk));
- sig->stime = cputime_add(sig->stime, task_stime(tsk));
+ task_times(tsk, &utime, &stime);
+ sig->utime = cputime_add(sig->utime, utime);
+ sig->stime = cputime_add(sig->stime, stime);
sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
sig->min_flt += tsk->min_flt;
sig->maj_flt += tsk->maj_flt;