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authorJason Low <jason.low2@hp.com>2015-10-14 19:07:53 (GMT)
committerThomas Gleixner <tglx@linutronix.de>2015-10-15 09:23:41 (GMT)
commit7c177d994eb9637302b79e80d331f48dfbe26368 (patch)
treec5160894bfb1ea109d73e45e2d3dc066c69cd24b /kernel/time
parent6035519fcf5aa17084b41790cdc584d881d82c03 (diff)
downloadlinux-7c177d994eb9637302b79e80d331f48dfbe26368.tar.xz
posix_cpu_timer: Optimize fastpath_timer_check()
In fastpath_timer_check(), the task_cputime() function is always called to compute the utime and stime values. However, this is not necessary if there are no per-thread timers to check for. This patch modifies the code such that we compute the task_cputime values only when there are per-thread timers set. Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: George Spelvin <linux@horizon.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-2-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/posix-cpu-timers.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 892e3da..aa4b6f4 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1117,17 +1117,12 @@ static inline int task_cputime_expired(const struct task_cputime *sample,
static inline int fastpath_timer_check(struct task_struct *tsk)
{
struct signal_struct *sig;
- cputime_t utime, stime;
-
- task_cputime(tsk, &utime, &stime);
if (!task_cputime_zero(&tsk->cputime_expires)) {
- struct task_cputime task_sample = {
- .utime = utime,
- .stime = stime,
- .sum_exec_runtime = tsk->se.sum_exec_runtime
- };
+ struct task_cputime task_sample;
+ task_cputime(tsk, &task_sample.utime, &task_sample.stime);
+ task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
return 1;
}