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authorJason Low <jason.low2@hp.com>2015-10-14 15:07:53 -0400
committerThomas Gleixner <tglx@linutronix.de>2015-10-15 05:23:41 -0400
commit7c177d994eb9637302b79e80d331f48dfbe26368 (patch)
treec5160894bfb1ea109d73e45e2d3dc066c69cd24b /kernel/time/posix-cpu-timers.c
parent6035519fcf5aa17084b41790cdc584d881d82c03 (diff)
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/posix-cpu-timers.c')
-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 892e3dae0aac..aa4b6f4f3b5e 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,
1117static inline int fastpath_timer_check(struct task_struct *tsk) 1117static inline int fastpath_timer_check(struct task_struct *tsk)
1118{ 1118{
1119 struct signal_struct *sig; 1119 struct signal_struct *sig;
1120 cputime_t utime, stime;
1121
1122 task_cputime(tsk, &utime, &stime);
1123 1120
1124 if (!task_cputime_zero(&tsk->cputime_expires)) { 1121 if (!task_cputime_zero(&tsk->cputime_expires)) {
1125 struct task_cputime task_sample = { 1122 struct task_cputime task_sample;
1126 .utime = utime,
1127 .stime = stime,
1128 .sum_exec_runtime = tsk->se.sum_exec_runtime
1129 };
1130 1123
1124 task_cputime(tsk, &task_sample.utime, &task_sample.stime);
1125 task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
1131 if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) 1126 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1132 return 1; 1127 return 1;
1133 } 1128 }