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Subject[PATCH] TIMER Refactoring: avoid unnecessary recalculation of cpu skew and remove duplication
commit 2a31a3b1db7898cf2360b628fa8717d85aac3e22
Author: Matyas Janos <mjanos5@gmail.com>
Date: Tue Oct 18 21:20:31 2016 +0200

Refactoring: avoid unnecessary recalculation of cpu skew and remove duplication

Signed-off-by: Matyas Janos <mjanos5@gmail.com>
---
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index a5221abb4594..f6de4d68e652 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -275,6 +275,7 @@ static unsigned long round_jiffies_common(unsigned long j, int cpu,
{
int rem;
unsigned long original = j;
+ unsigned long cpu_skew = cpu * 3;

/*
* We don't want all cpus firing their timers at once hitting the
@@ -284,7 +285,7 @@ static unsigned long round_jiffies_common(unsigned long j, int cpu,
* The skew is done by adding 3*cpunr, then round, then subtract this
* extra offset again.
*/
- j += cpu * 3;
+ j += cpu_skew;

rem = j % HZ;

@@ -295,13 +296,13 @@ static unsigned long round_jiffies_common(unsigned long j, int cpu,
* as cutoff for this rounding as an extreme upper bound for this.
* But never round down if @force_up is set.
*/
- if (rem < HZ/4 && !force_up) /* round down */
- j = j - rem;
- else /* round up */
- j = j - rem + HZ;
+ j -= rem; /* round down by default */
+
+ if (rem >= HZ / 4 || force_up)
+ j += HZ; /* round up */

/* now that we have rounded, subtract the extra skew again */
- j -= cpu * 3;
+ j -= cpu_skew;

/*
* Make sure j is still in the future. Otherwise return the
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