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posix_timers: New API to prevent from stopping the tick when timers are running

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Bring a new helper that the full dynticks infrastructure can
call in order to know if it can safely stop the tick from
the posix cpu timers subsystem point of view.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Frederic Weisbecker 2013-04-19 16:17:38 +02:00
parent a85721601a
commit 555347f6c0
2 changed files with 28 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

2
include/linux/posix-timers.h
View file

@ -122,6 +122,8 @@ void run_posix_cpu_timers(struct task_struct *task);
void posix_cpu_timers_exit(struct task_struct *task); void posix_cpu_timers_exit(struct task_struct *task);
void posix_cpu_timers_exit_group(struct task_struct *task); void posix_cpu_timers_exit_group(struct task_struct *task);
bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk);
void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx, void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval); cputime_t *newval, cputime_t *oldval);

41
kernel/posix-cpu-timers.c
View file

@ -155,6 +155,21 @@ static void bump_cpu_timer(struct k_itimer *timer,
} }
} }
/**
* task_cputime_zero - Check a task_cputime struct for all zero fields.
*
* @cputime: The struct to compare.
*
* Checks @cputime to see if all fields are zero. Returns true if all fields
* are zero, false if any field is nonzero.
*/
static inline int task_cputime_zero(const struct task_cputime *cputime)
{
if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
return 1;
return 0;
}
static inline cputime_t prof_ticks(struct task_struct *p) static inline cputime_t prof_ticks(struct task_struct *p)
{ {
cputime_t utime, stime; cputime_t utime, stime;
@ -654,6 +669,17 @@ static void posix_cpu_timer_kick_nohz(void)
{ {
schedule_work(&nohz_kick_work); schedule_work(&nohz_kick_work);
} }
bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
{
if (!task_cputime_zero(&tsk->cputime_expires))
return true;
if (tsk->signal->cputimer.running)
return true;
return false;
}
#else #else
static inline void posix_cpu_timer_kick_nohz(void) { } static inline void posix_cpu_timer_kick_nohz(void) { }
#endif #endif
@ -1032,21 +1058,6 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
} }
} }
/**
* task_cputime_zero - Check a task_cputime struct for all zero fields.
*
* @cputime: The struct to compare.
*
* Checks @cputime to see if all fields are zero. Returns true if all fields
* are zero, false if any field is nonzero.
*/
static inline int task_cputime_zero(const struct task_cputime *cputime)
{
if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
return 1;
return 0;
}
/* /*
* Check for any per-thread CPU timers that have fired and move them * Check for any per-thread CPU timers that have fired and move them
* off the tsk->*_timers list onto the firing list. Per-thread timers * off the tsk->*_timers list onto the firing list. Per-thread timers