* [RFC PATCH 0/6] cpu-timers patches
@ 2009-12-09 9:39 Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 1/6] cpu-timers: simplify RLIMIT_CPU handling Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Here are patches for cpu-timers I mainly wrote to not call
thread_group_cputime() in fastpath_timer_check(), which we
discuss in this thread:
http://thread.gmane.org/gmane.linux.kernel/909349/focus=912327
On the way I fix some other bugs (SIGEV_NONE timer, old increase value
in timer_settime()) and do other cleanups and optimizations, patch 3
however increase time when sighand->siglock is held.
0001-cpu-timers-simplify-RLIMIT_CPU-handling.patch
0002-cpu-timers-cleanup-arm_timer.patch
0003-cpu-timers-return-true-old-increase-value-in-timer_.patch
0004-cpu-timers-change-SIGEV_NONE-timer-handling.patch
0005-cpu-timer-change-arm_timer-locking.patch
0006-cpu-timers-optimize-run_posix_cpu_timers.patch
Cheers
Stanislaw
^ permalink raw reply [flat|nested] 7+ messages in thread
* [RFC PATCH 1/6] cpu-timers: simplify RLIMIT_CPU handling
2009-12-09 9:39 [RFC PATCH 0/6] cpu-timers patches Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 2/6] cpu-timers: cleanup arm_timer() Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Let always set expiration (prof_exp) cache when settings itimers,
POSIX 1.b timers and RLIMIT_CPU. Together with settings expiration
cache in fork, this allow to remove RLIMIT_CPU != inf check in
fastpath_timer_check() and do some other cleanups.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 74 ++++++++++++++++-----------------------------
1 files changed, 26 insertions(+), 48 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 438ff45..137d991 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -11,19 +11,17 @@
#include <trace/events/timer.h>
/*
- * Called after updating RLIMIT_CPU to set timer expiration if necessary.
+ * Called after updating RLIMIT_CPU to run cputimer and set expiration cache
+ * if necessary. Need siglock since cpu timers can work with cputime_expires
+ * as well.
*/
void update_rlimit_cpu(unsigned long rlim_new)
{
cputime_t cputime = secs_to_cputime(rlim_new);
- struct signal_struct *const sig = current->signal;
- if (cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) ||
- cputime_gt(sig->it[CPUCLOCK_PROF].expires, cputime)) {
- spin_lock_irq(¤t->sighand->siglock);
- set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
- spin_unlock_irq(¤t->sighand->siglock);
- }
+ spin_lock_irq(¤t->sighand->siglock);
+ set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
+ spin_unlock_irq(¤t->sighand->siglock);
}
static int check_clock(const clockid_t which_clock)
@@ -564,7 +562,6 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
struct list_head *head, *listpos;
struct cpu_timer_list *const nt = &timer->it.cpu;
struct cpu_timer_list *next;
- unsigned long i;
head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
p->cpu_timers : p->signal->cpu_timers);
@@ -630,20 +627,11 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
default:
BUG();
case CPUCLOCK_VIRT:
- if (expires_le(sig->it[CPUCLOCK_VIRT].expires,
- exp->cpu))
- break;
- sig->cputime_expires.virt_exp = exp->cpu;
- break;
+ if (expires_gt(sig->cputime_expires.virt_exp, exp->cpu))
+ sig->cputime_expires.virt_exp = exp->cpu;
case CPUCLOCK_PROF:
- if (expires_le(sig->it[CPUCLOCK_PROF].expires,
- exp->cpu))
- break;
- i = sig->rlim[RLIMIT_CPU].rlim_cur;
- if (i != RLIM_INFINITY &&
- i <= cputime_to_secs(exp->cpu))
- break;
- sig->cputime_expires.prof_exp = exp->cpu;
+ if (expires_gt(sig->cputime_expires.prof_exp, exp->cpu))
+ sig->cputime_expires.prof_exp = exp->cpu;
break;
case CPUCLOCK_SCHED:
sig->cputime_expires.sched_exp = exp->sched;
@@ -1382,7 +1370,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
return 1;
}
- return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
+ return 0;
}
/*
@@ -1448,21 +1436,23 @@ void run_posix_cpu_timers(struct task_struct *tsk)
}
/*
- * Set one of the process-wide special case CPU timers.
+ * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
* The tsk->sighand->siglock must be held by the caller.
- * The *newval argument is relative and we update it to be absolute, *oldval
- * is absolute and we update it to be relative.
*/
void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval)
{
union cpu_time_count now;
- struct list_head *head;
BUG_ON(clock_idx == CPUCLOCK_SCHED);
cpu_timer_sample_group(clock_idx, tsk, &now);
if (oldval) {
+ /*
+ * We are setting itimer. The *newval argument is relative
+ * and we update it to be absolute, *oldval is absolute and
+ * we update it to be relative.
+ */
if (!cputime_eq(*oldval, cputime_zero)) {
if (cputime_le(*oldval, now.cpu)) {
/* Just about to fire. */
@@ -1475,33 +1465,21 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
if (cputime_eq(*newval, cputime_zero))
return;
*newval = cputime_add(*newval, now.cpu);
-
- /*
- * If the RLIMIT_CPU timer will expire before the
- * ITIMER_PROF timer, we have nothing else to do.
- */
- if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
- < cputime_to_secs(*newval))
- return;
}
/*
- * Check whether there are any process timers already set to fire
- * before this one. If so, we don't have anything more to do.
+ * Update expiration cache if we are the earliest timer
+ * or RLIMIT_CPU limits before any other timer expire.
*/
- head = &tsk->signal->cpu_timers[clock_idx];
- if (list_empty(head) ||
- cputime_ge(list_first_entry(head,
- struct cpu_timer_list, entry)->expires.cpu,
- *newval)) {
- switch (clock_idx) {
- case CPUCLOCK_PROF:
+ switch (clock_idx) {
+ case CPUCLOCK_PROF:
+ if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
tsk->signal->cputime_expires.prof_exp = *newval;
- break;
- case CPUCLOCK_VIRT:
+ break;
+ case CPUCLOCK_VIRT:
+ if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
tsk->signal->cputime_expires.virt_exp = *newval;
- break;
- }
+ break;
}
}
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH 2/6] cpu-timers: cleanup arm_timer()
2009-12-09 9:39 ` [RFC PATCH 1/6] cpu-timers: simplify RLIMIT_CPU handling Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 3/6] cpu-timers: return true old increase value in timer_settime() Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Updating expiration cache is messed in arm_timer(), clean it up.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 104 +++++++++++++++------------------------------
1 files changed, 35 insertions(+), 69 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 137d991..84589e9 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -546,97 +546,63 @@ static inline int expires_gt(cputime_t expires, cputime_t new_exp)
cputime_gt(expires, new_exp);
}
-static inline int expires_le(cputime_t expires, cputime_t new_exp)
-{
- return !cputime_eq(expires, cputime_zero) &&
- cputime_le(expires, new_exp);
-}
/*
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the tasklist_lock held
* for reading, and interrupts disabled.
*/
-static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
+static void arm_timer(struct k_itimer *timer)
{
struct task_struct *p = timer->it.cpu.task;
struct list_head *head, *listpos;
+ struct task_cputime *cputime_expires;
struct cpu_timer_list *const nt = &timer->it.cpu;
struct cpu_timer_list *next;
- head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
- p->cpu_timers : p->signal->cpu_timers);
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ head = p->cpu_timers;
+ cputime_expires = &p->cputime_expires;
+ } else {
+ head = p->signal->cpu_timers;
+ cputime_expires = &p->signal->cputime_expires;
+ }
head += CPUCLOCK_WHICH(timer->it_clock);
BUG_ON(!irqs_disabled());
spin_lock(&p->sighand->siglock);
listpos = head;
- if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
- list_for_each_entry(next, head, entry) {
- if (next->expires.sched > nt->expires.sched)
- break;
- listpos = &next->entry;
- }
- } else {
- list_for_each_entry(next, head, entry) {
- if (cputime_gt(next->expires.cpu, nt->expires.cpu))
- break;
- listpos = &next->entry;
- }
+ list_for_each_entry(next, head, entry) {
+ if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
+ break;
+ listpos = &next->entry;
}
list_add(&nt->entry, listpos);
if (listpos == head) {
+ union cpu_time_count *exp = &nt->expires;
+
/*
- * We are the new earliest-expiring timer.
- * If we are a thread timer, there can always
- * be a process timer telling us to stop earlier.
+ * We are the new earliest-expiring POSIX 1.b timer, hence
+ * need to update expiration cache. Take into account that
+ * for process timers we share expiration cache with itimers
+ * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- union cpu_time_count *exp = &nt->expires;
-
- switch (CPUCLOCK_WHICH(timer->it_clock)) {
- default:
- BUG();
- case CPUCLOCK_PROF:
- if (expires_gt(p->cputime_expires.prof_exp,
- exp->cpu))
- p->cputime_expires.prof_exp = exp->cpu;
- break;
- case CPUCLOCK_VIRT:
- if (expires_gt(p->cputime_expires.virt_exp,
- exp->cpu))
- p->cputime_expires.virt_exp = exp->cpu;
- break;
- case CPUCLOCK_SCHED:
- if (p->cputime_expires.sched_exp == 0 ||
- p->cputime_expires.sched_exp > exp->sched)
- p->cputime_expires.sched_exp =
- exp->sched;
- break;
- }
- } else {
- struct signal_struct *const sig = p->signal;
- union cpu_time_count *exp = &timer->it.cpu.expires;
-
- /*
- * For a process timer, set the cached expiration time.
- */
- switch (CPUCLOCK_WHICH(timer->it_clock)) {
- default:
- BUG();
- case CPUCLOCK_VIRT:
- if (expires_gt(sig->cputime_expires.virt_exp, exp->cpu))
- sig->cputime_expires.virt_exp = exp->cpu;
- case CPUCLOCK_PROF:
- if (expires_gt(sig->cputime_expires.prof_exp, exp->cpu))
- sig->cputime_expires.prof_exp = exp->cpu;
- break;
- case CPUCLOCK_SCHED:
- sig->cputime_expires.sched_exp = exp->sched;
- break;
- }
+ switch (CPUCLOCK_WHICH(timer->it_clock)) {
+ case CPUCLOCK_PROF:
+ if (expires_gt(cputime_expires->prof_exp, exp->cpu))
+ cputime_expires->prof_exp = exp->cpu;
+ break;
+ case CPUCLOCK_VIRT:
+ if (expires_gt(cputime_expires->virt_exp, exp->cpu))
+ cputime_expires->virt_exp = exp->cpu;
+ break;
+ case CPUCLOCK_SCHED:
+ if (cputime_expires->sched_exp == 0 ||
+ cputime_expires->sched_exp > exp->sched)
+ cputime_expires->sched_exp = exp->sched;
+ break;
}
}
@@ -818,7 +784,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
if (new_expires.sched != 0 &&
(timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
cpu_time_before(timer->it_clock, val, new_expires)) {
- arm_timer(timer, val);
+ arm_timer(timer);
}
read_unlock(&tasklist_lock);
@@ -1278,7 +1244,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
/*
* Now re-arm for the new expiry time.
*/
- arm_timer(timer, now);
+ arm_timer(timer);
out_unlock:
read_unlock(&tasklist_lock);
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH 3/6] cpu-timers: return true old increase value in timer_settime()
2009-12-09 9:39 ` [RFC PATCH 2/6] cpu-timers: cleanup arm_timer() Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 4/6] cpu-timers: change SIGEV_NONE timer handling Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 84589e9..4716c8c 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -675,7 +675,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
struct itimerspec *new, struct itimerspec *old)
{
struct task_struct *p = timer->it.cpu.task;
- union cpu_time_count old_expires, new_expires, val;
+ union cpu_time_count old_expires, new_expires, old_incr, val;
int ret;
if (unlikely(p == NULL)) {
@@ -706,6 +706,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
BUG_ON(!irqs_disabled());
ret = 0;
+ old_incr = timer->it.cpu.incr;
spin_lock(&p->sighand->siglock);
old_expires = timer->it.cpu.expires;
if (unlikely(timer->it.cpu.firing)) {
@@ -821,7 +822,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
out:
if (old) {
sample_to_timespec(timer->it_clock,
- timer->it.cpu.incr, &old->it_interval);
+ old_incr, &old->it_interval);
}
return ret;
}
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH 4/6] cpu-timers: change SIGEV_NONE timer handling
2009-12-09 9:39 ` [RFC PATCH 3/6] cpu-timers: return true old increase value in timer_settime() Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 5/6] cpu-timers: change arm_timer() locking Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Currently when user setup timer without associated signal and process
not use any other cpu timers, we are running tsk->signal->cputimer
forewer, change that.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 28 ++++++----------------------
1 files changed, 6 insertions(+), 22 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 4716c8c..08506ff 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -614,7 +614,12 @@ static void arm_timer(struct k_itimer *timer)
*/
static void cpu_timer_fire(struct k_itimer *timer)
{
- if (unlikely(timer->sigq == NULL)) {
+ if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
+ /*
+ * User don't want any signal.
+ */
+ timer->it.cpu.expires.sched = 0;
+ } else if (unlikely(timer->sigq == NULL)) {
/*
* This a special case for clock_nanosleep,
* not a normal timer from sys_timer_create.
@@ -783,7 +788,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
*/
timer->it.cpu.expires = new_expires;
if (new_expires.sched != 0 &&
- (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
cpu_time_before(timer->it_clock, val, new_expires)) {
arm_timer(timer);
}
@@ -808,7 +812,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
timer->it_overrun = -1;
if (new_expires.sched != 0 &&
- (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
!cpu_time_before(timer->it_clock, val, new_expires)) {
/*
* The designated time already passed, so we notify
@@ -882,25 +885,6 @@ void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
read_unlock(&tasklist_lock);
}
- if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
- if (timer->it.cpu.incr.sched == 0 &&
- cpu_time_before(timer->it_clock,
- timer->it.cpu.expires, now)) {
- /*
- * Do-nothing timer expired and has no reload,
- * so it's as if it was never set.
- */
- timer->it.cpu.expires.sched = 0;
- itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
- return;
- }
- /*
- * Account for any expirations and reloads that should
- * have happened.
- */
- bump_cpu_timer(timer, now);
- }
-
if (unlikely(clear_dead)) {
/*
* We've noticed that the thread is dead, but
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH 5/6] cpu-timers: change arm_timer() locking
2009-12-09 9:39 ` [RFC PATCH 4/6] cpu-timers: change SIGEV_NONE timer handling Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 6/6] cpu-timers: optimize run_posix_cpu_timers() Stanislaw Gruszka
0 siblings, 1 reply; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
Spread p->sighand->siglock locking scope to assure signal->cputimer
is always running when we are setuping signal->cputime_expires.
This further assure we do not iterate over all threads in
fastpath_timer_check() when calling thread_group_cputimer().
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 14 +++++++-------
1 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 08506ff..68d4045 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -549,7 +549,7 @@ static inline int expires_gt(cputime_t expires, cputime_t new_exp)
/*
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the tasklist_lock held
- * for reading, and interrupts disabled.
+ * for reading, interrupts disabled and p->sighand->siglock taken.
*/
static void arm_timer(struct k_itimer *timer)
{
@@ -568,9 +568,6 @@ static void arm_timer(struct k_itimer *timer)
}
head += CPUCLOCK_WHICH(timer->it_clock);
- BUG_ON(!irqs_disabled());
- spin_lock(&p->sighand->siglock);
-
listpos = head;
list_for_each_entry(next, head, entry) {
if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
@@ -605,8 +602,6 @@ static void arm_timer(struct k_itimer *timer)
break;
}
}
-
- spin_unlock(&p->sighand->siglock);
}
/*
@@ -719,7 +714,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
ret = TIMER_RETRY;
} else
list_del_init(&timer->it.cpu.entry);
- spin_unlock(&p->sighand->siglock);
/*
* We need to sample the current value to convert the new
@@ -773,6 +767,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
* disable this firing since we are already reporting
* it as an overrun (thanks to bump_cpu_timer above).
*/
+ spin_unlock(&p->sighand->siglock);
read_unlock(&tasklist_lock);
goto out;
}
@@ -792,6 +787,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
arm_timer(timer);
}
+ spin_unlock(&p->sighand->siglock);
read_unlock(&tasklist_lock);
/*
@@ -1201,6 +1197,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
goto out;
}
read_lock(&tasklist_lock); /* arm_timer needs it. */
+ spin_lock(&p->sighand->siglock);
} else {
read_lock(&tasklist_lock);
if (unlikely(p->signal == NULL)) {
@@ -1221,6 +1218,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
clear_dead_task(timer, now);
goto out_unlock;
}
+ spin_lock(&p->sighand->siglock);
cpu_timer_sample_group(timer->it_clock, p, &now);
bump_cpu_timer(timer, now);
/* Leave the tasklist_lock locked for the call below. */
@@ -1229,7 +1227,9 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
/*
* Now re-arm for the new expiry time.
*/
+ BUG_ON(!irqs_disabled());
arm_timer(timer);
+ spin_unlock(&p->sighand->siglock);
out_unlock:
read_unlock(&tasklist_lock);
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH 6/6] cpu-timers: optimize run_posix_cpu_timers()
2009-12-09 9:39 ` [RFC PATCH 5/6] cpu-timers: change arm_timer() locking Stanislaw Gruszka
@ 2009-12-09 9:39 ` Stanislaw Gruszka
0 siblings, 0 replies; 7+ messages in thread
From: Stanislaw Gruszka @ 2009-12-09 9:39 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, Oleg Nesterov, Peter Zijlstra, Hidetoshi Seto,
Balbir Singh, linux-kernel, Stanislaw Gruszka
We can optimize and simplify things taking into account signal->cputimer
is always running when we have configured any process wide cpu timer.
In check_process_timers(), we don't have to check if new updated value
of signal->cputime_expires is smaller, since we maintain new first
expiration time ({prof,virt,sched}_expires) in code flow and all other
writes to expiration cache are protected by sighand->siglock .
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 81 ++++++++++++++++++---------------------------
1 files changed, 32 insertions(+), 49 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 68d4045..69a9c27 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -995,14 +995,11 @@ 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)
- return;
-
spin_lock_irqsave(&cputimer->lock, flags);
cputimer->running = 0;
spin_unlock_irqrestore(&cputimer->lock, flags);
@@ -1042,6 +1039,23 @@ 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_eq(cputime->utime, cputime_zero) &&
+ cputime_eq(cputime->stime, cputime_zero) &&
+ cputime->sum_exec_runtime == 0)
+ return 1;
+ return 0;
+}
+
/*
* 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
@@ -1058,19 +1072,6 @@ static void check_process_timers(struct task_struct *tsk,
struct task_cputime cputime;
/*
- * Don't sample the current process CPU clocks if there are no timers.
- */
- if (list_empty(&timers[CPUCLOCK_PROF]) &&
- cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) &&
- sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
- list_empty(&timers[CPUCLOCK_VIRT]) &&
- cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
- list_empty(&timers[CPUCLOCK_SCHED])) {
- stop_process_timers(tsk);
- return;
- }
-
- /*
* Collect the current process totals.
*/
thread_group_cputimer(tsk, &cputime);
@@ -1157,18 +1158,12 @@ static void check_process_timers(struct task_struct *tsk,
}
}
- if (!cputime_eq(prof_expires, cputime_zero) &&
- (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
- cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
- sig->cputime_expires.prof_exp = prof_expires;
- if (!cputime_eq(virt_expires, cputime_zero) &&
- (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
- cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
- sig->cputime_expires.virt_exp = virt_expires;
- if (sched_expires != 0 &&
- (sig->cputime_expires.sched_exp == 0 ||
- sig->cputime_expires.sched_exp > sched_expires))
- sig->cputime_expires.sched_exp = sched_expires;
+ sig->cputime_expires.prof_exp = prof_expires;
+ sig->cputime_expires.virt_exp = virt_expires;
+ sig->cputime_expires.sched_exp = sched_expires;
+
+ if (task_cputime_zero(&sig->cputime_expires))
+ stop_process_timers(sig);
}
/*
@@ -1241,23 +1236,6 @@ out:
}
/**
- * 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_eq(cputime->utime, cputime_zero) &&
- cputime_eq(cputime->stime, cputime_zero) &&
- cputime->sum_exec_runtime == 0)
- return 1;
- return 0;
-}
-
-/**
* task_cputime_expired - Compare two task_cputime entities.
*
* @sample: The task_cputime structure to be checked for expiration.
@@ -1313,7 +1291,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
}
sig = tsk->signal;
- if (!task_cputime_zero(&sig->cputime_expires)) {
+ if (sig->cputimer.running) {
struct task_cputime group_sample;
thread_group_cputimer(tsk, &group_sample);
@@ -1350,7 +1328,12 @@ void run_posix_cpu_timers(struct task_struct *tsk)
* put them on the firing list.
*/
check_thread_timers(tsk, &firing);
- check_process_timers(tsk, &firing);
+ /*
+ * If there are any active process wide timers (POSIX 1.b, itimers,
+ * RLIMIT_CPU) cputimer must be running.
+ */
+ if (tsk->signal->cputimer.running)
+ check_process_timers(tsk, &firing);
/*
* We must release these locks before taking any timer's lock.
--
1.6.2.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2009-12-09 9:43 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-12-09 9:39 [RFC PATCH 0/6] cpu-timers patches Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 1/6] cpu-timers: simplify RLIMIT_CPU handling Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 2/6] cpu-timers: cleanup arm_timer() Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 3/6] cpu-timers: return true old increase value in timer_settime() Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 4/6] cpu-timers: change SIGEV_NONE timer handling Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 5/6] cpu-timers: change arm_timer() locking Stanislaw Gruszka
2009-12-09 9:39 ` [RFC PATCH 6/6] cpu-timers: optimize run_posix_cpu_timers() Stanislaw Gruszka
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