cputime: Optimize jiffies_to_cputime(1)
For powerpc with CONFIG_VIRT_CPU_ACCOUNTING
jiffies_to_cputime(1) is not compile time constant and run time
calculations are quite expensive. To optimize we use
precomputed value. For all other architectures is is
preprocessor definition.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <1248862529-6063-5-git-send-email-sgruszka@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/itimer.c b/kernel/itimer.c
index 21adff7..8078a32 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -64,7 +64,7 @@
if (cputime_le(cval, t))
/* about to fire */
- cval = jiffies_to_cputime(1);
+ cval = cputime_one_jiffy;
else
cval = cputime_sub(cval, t);
}
@@ -161,7 +161,7 @@
if (!cputime_eq(cval, cputime_zero) ||
!cputime_eq(nval, cputime_zero)) {
if (cputime_gt(nval, cputime_zero))
- nval = cputime_add(nval, jiffies_to_cputime(1));
+ nval = cputime_add(nval, cputime_one_jiffy);
set_process_cpu_timer(tsk, clock_id, &nval, &cval);
}
it->expires = nval;
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 69c9237435..18bdde6 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1086,7 +1086,7 @@
it->error += it->incr_error;
if (it->error >= onecputick) {
it->expires = cputime_sub(it->expires,
- jiffies_to_cputime(1));
+ cputime_one_jiffy);
it->error -= onecputick;
}
} else
@@ -1461,7 +1461,7 @@
if (!cputime_eq(*oldval, cputime_zero)) {
if (cputime_le(*oldval, now.cpu)) {
/* Just about to fire. */
- *oldval = jiffies_to_cputime(1);
+ *oldval = cputime_one_jiffy;
} else {
*oldval = cputime_sub(*oldval, now.cpu);
}
@@ -1712,7 +1712,7 @@
register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
- cputime_to_timespec(jiffies_to_cputime(1), &ts);
+ cputime_to_timespec(cputime_one_jiffy, &ts);
onecputick = ts.tv_nsec;
WARN_ON(ts.tv_sec != 0);
diff --git a/kernel/sched.c b/kernel/sched.c
index 1b59e26..8f977d5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5031,17 +5031,16 @@
*/
void account_process_tick(struct task_struct *p, int user_tick)
{
- cputime_t one_jiffy = jiffies_to_cputime(1);
- cputime_t one_jiffy_scaled = cputime_to_scaled(one_jiffy);
+ cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
struct rq *rq = this_rq();
if (user_tick)
- account_user_time(p, one_jiffy, one_jiffy_scaled);
+ account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
- account_system_time(p, HARDIRQ_OFFSET, one_jiffy,
+ account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
one_jiffy_scaled);
else
- account_idle_time(one_jiffy);
+ account_idle_time(cputime_one_jiffy);
}
/*