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;