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Message-Id: <1263990868-8119-2-git-send-email-sgruszka@redhat.com>
Date: Wed, 20 Jan 2010 13:34:23 +0100
From: Stanislaw Gruszka <sgruszka@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>, Oleg Nesterov <oleg@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
Balbir Singh <balbir@...ibm.com>, linux-kernel@...r.kernel.org,
Stanislaw Gruszka <sgruszka@...hat.com>
Subject: [PATCH 1/6 -mm] cpu-timers: simplify RLIMIT_CPU handling
Let always set signal->cputime_expires expiration cache when setting
new itimer, POSIX 1.b timer, and RLIMIT_CPU. Since we are initializing
prof_exp expiration cache during fork(), this allow to remove
"RLIMIT_CPU != inf" check from fastpath_timer_check() and do some other
cleanups.
Checked against regression using test cases from:
http://marc.info/?l=linux-kernel&m=123749066504641&w=4
http://marc.info/?l=linux-kernel&m=123811277916642&w=2
Signed-off-by: Stanislaw Gruszka <sgruszka@...hat.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 9931a64..3e31d51 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 cpu timer and update
+ * tsk->signal->cputime_expires expiration cache if necessary. Needs siglock
+ * protection since other code may update expiration cache as well.
*/
void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
{
cputime_t cputime = secs_to_cputime(rlim_new);
- struct signal_struct *const sig = task->signal;
- if (cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) ||
- cputime_gt(sig->it[CPUCLOCK_PROF].expires, cputime)) {
- spin_lock_irq(&task->sighand->siglock);
- set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
- spin_unlock_irq(&task->sighand->siglock);
- }
+ spin_lock_irq(&task->sighand->siglock);
+ set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
+ spin_unlock_irq(&task->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;
@@ -1386,7 +1374,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
return 1;
}
- return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
+ return 0;
}
/*
@@ -1452,21 +1440,23 @@ 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 *oldval is absolute and we update
+ * it to be relative, *newval argument is relative and we update
+ * it to be absolute.
+ */
if (!cputime_eq(*oldval, cputime_zero)) {
if (cputime_le(*oldval, now.cpu)) {
/* Just about to fire. */
@@ -1479,33 +1469,21 @@ 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 eventually
+ * RLIMIT_CPU limit is earlier than prof_exp cpu 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
--
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