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Message-Id: <1440559068-29680-3-git-send-email-jason.low2@hp.com>
Date: Tue, 25 Aug 2015 20:17:47 -0700
From: Jason Low <jason.low2@...com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Oleg Nesterov <oleg@...hat.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org,
Frederic Weisbecker <fweisbec@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Davidlohr Bueso <dave@...olabs.net>,
Steven Rostedt <rostedt@...dmis.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Terry Rudd <terry.rudd@...com>, Rik van Riel <riel@...hat.com>,
Scott J Norton <scott.norton@...com>,
Jason Low <jason.low2@...com>
Subject: [PATCH 2/3] timer: Check thread timers only when there are active thread timers
The fastpath_timer_check() contains logic to check for if any timers
are set by checking if !task_cputime_zero(). Similarly, we can do this
before calling check_thread_timers(). In the case where there
are only process-wide timers, this will skip all the computations for
the per-thread timers when there are no per-thread timers.
Signed-off-by: Jason Low <jason.low2@...com>
---
kernel/time/posix-cpu-timers.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 02596ff..535bef5 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1168,11 +1168,13 @@ void run_posix_cpu_timers(struct task_struct *tsk)
if (!lock_task_sighand(tsk, &flags))
return;
/*
- * Here we take off tsk->signal->cpu_timers[N] and
- * tsk->cpu_timers[N] all the timers that are firing, and
- * put them on the firing list.
+ * If there are active per-thread timers, take off
+ * tsk->signal->cpu_timers[N] and tsk->cpu_timers[N] all the
+ * timers that are firing, and put them on the firing list.
*/
- check_thread_timers(tsk, &firing);
+ if (!task_cputime_zero(&tsk->cputime_expires))
+ check_thread_timers(tsk, &firing);
+
/*
* If there are any active process wide timers (POSIX 1.b, itimers,
* RLIMIT_CPU) cputimer must be running.
--
1.7.2.5
--
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