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Subject[PATCH 3/3] posix_cpu_timers: Consolidate expired timers check
Date
Consolidate the common code amongst per thread and per process
timers list on tick time.

List traversal, expiry check and subsequent updates can be
shared in a common helper.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
---
kernel/posix-cpu-timers.c | 118 +++++++++++++--------------------------------
1 files changed, 33 insertions(+), 85 deletions(-)

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index bb03633..19df00a 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -812,6 +812,28 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
}
}

+static unsigned long long
+check_timers_list(struct list_head *timers,
+ struct list_head *firing,
+ unsigned long long curr)
+{
+ int maxfire = 20;
+
+ while (!list_empty(timers)) {
+ struct cpu_timer_list *t;
+
+ t = list_first_entry(timers, struct cpu_timer_list, entry);
+
+ if (!--maxfire || curr < t->expires)
+ return t->expires;
+
+ t->firing = 1;
+ list_move_tail(&t->entry, firing);
+ }
+
+ return 0;
+}
+
/*
* Check for any per-thread CPU timers that have fired and move them off
* the tsk->cpu_timers[N] list onto the firing list. Here we update the
@@ -820,54 +842,20 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
static void check_thread_timers(struct task_struct *tsk,
struct list_head *firing)
{
- int maxfire;
struct list_head *timers = tsk->cpu_timers;
struct signal_struct *const sig = tsk->signal;
+ struct task_cputime *tsk_expires = &tsk->cputime_expires;
+ unsigned long long expires;
unsigned long soft;

- maxfire = 20;
- tsk->cputime_expires.prof_exp = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *t = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || prof_ticks(tsk) < t->expires) {
- tsk->cputime_expires.prof_exp = expires_to_cputime(t->expires);
- break;
- }
- t->firing = 1;
- list_move_tail(&t->entry, firing);
- }
+ expires = check_timers_list(timers, firing, prof_ticks(tsk));
+ tsk_expires->prof_exp = expires_to_cputime(expires);

- ++timers;
- maxfire = 20;
- tsk->cputime_expires.virt_exp = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *t = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || virt_ticks(tsk) < t->expires) {
- tsk->cputime_expires.virt_exp = expires_to_cputime(t->expires);
- break;
- }
- t->firing = 1;
- list_move_tail(&t->entry, firing);
- }
+ expires = check_timers_list(++timers, firing, virt_ticks(tsk));
+ tsk_expires->virt_exp = expires_to_cputime(expires);

- ++timers;
- maxfire = 20;
- tsk->cputime_expires.sched_exp = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *t = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || tsk->se.sum_exec_runtime < t->expires) {
- tsk->cputime_expires.sched_exp = t->expires;
- break;
- }
- t->firing = 1;
- list_move_tail(&t->entry, firing);
- }
+ tsk_expires->sched_exp = check_timers_list(++timers, firing,
+ tsk->se.sum_exec_runtime);

/*
* Check for the special case thread timers.
@@ -966,7 +954,6 @@ static inline int task_cputime_zero(const struct task_cputime *cputime)
static void check_process_timers(struct task_struct *tsk,
struct list_head *firing)
{
- int maxfire;
struct signal_struct *const sig = tsk->signal;
unsigned long long utime, ptime, virt_expires, prof_expires;
unsigned long long sum_sched_runtime, sched_expires;
@@ -981,49 +968,10 @@ static void check_process_timers(struct task_struct *tsk,
utime = cputime_to_expires(cputime.utime);
ptime = utime + cputime_to_expires(cputime.stime);
sum_sched_runtime = cputime.sum_exec_runtime;
- maxfire = 20;
- prof_expires = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *tl = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || ptime < tl->expires) {
- prof_expires = tl->expires;
- break;
- }
- tl->firing = 1;
- list_move_tail(&tl->entry, firing);
- }

- ++timers;
- maxfire = 20;
- virt_expires = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *tl = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || utime < tl->expires) {
- virt_expires = tl->expires;
- break;
- }
- tl->firing = 1;
- list_move_tail(&tl->entry, firing);
- }
-
- ++timers;
- maxfire = 20;
- sched_expires = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *tl = list_first_entry(timers,
- struct cpu_timer_list,
- entry);
- if (!--maxfire || sum_sched_runtime < tl->expires) {
- sched_expires = tl->expires;
- break;
- }
- tl->firing = 1;
- list_move_tail(&tl->entry, firing);
- }
+ prof_expires = check_timers_list(timers, firing, ptime);
+ virt_expires = check_timers_list(++timers, firing, utime);
+ sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);

/*
* Check for the special case process timers.
--
1.7.5.4


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