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posix-cpu-timers: Reset expire cache when no timer is running 

When a process deletes cpu timer or a timer expires we do not clear
the expiration cache sig->cputimer_expires.

As a result the fastpath_timer_check() which prevents us to loop over
all threads in case no timer is active is not working and we run the
slow path needlessly on every tick.

Zero sig->cputimer_expires in stop_process_timers().

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Spencer Candland <spencer@bluehost.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Stanislaw Gruszka 2010-03-11 14:04:31 -08:00 committed by Thomas Gleixner
parent 829b6c1ef4
commit 15365c108e
1 changed files with 7 additions and 3 deletions
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10
kernel/posix-cpu-timers.c
View File

@ -1060,9 +1060,9 @@ static void check_thread_timers(struct task_struct *tsk,
}
}
static void stop_process_timers(struct task_struct *tsk)
static void stop_process_timers(struct signal_struct *sig)
{
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
struct thread_group_cputimer *cputimer = &sig->cputimer;
unsigned long flags;
if (!cputimer->running)
@ -1071,6 +1071,10 @@ static void stop_process_timers(struct task_struct *tsk)
spin_lock_irqsave(&cputimer->lock, flags);
cputimer->running = 0;
spin_unlock_irqrestore(&cputimer->lock, flags);
sig->cputime_expires.prof_exp = cputime_zero;
sig->cputime_expires.virt_exp = cputime_zero;
sig->cputime_expires.sched_exp = 0;
}
static u32 onecputick;
@ -1131,7 +1135,7 @@ static void check_process_timers(struct task_struct *tsk,
list_empty(&timers[CPUCLOCK_VIRT]) &&
cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
list_empty(&timers[CPUCLOCK_SCHED])) {
stop_process_timers(tsk);
stop_process_timers(sig);
return;
}