linux-kernel - [PATCH v2 5/8] sched: Eliminate the ts->idle

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Date:	Sun, 9 May 2010 08:24:39 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, davej@...hat.com
Subject: [PATCH v2  5/8] sched: Eliminate the ts->idle_lastupdate field

From: Arjan van de Ven <arjan@...ux.intel.com>

Now that the only user of ts->idle_lastupdate is update_ts_time_stats(),
the entire field can be eliminated.

In update_ts_time_stats(), idle_lastupdate is first set to "now",
and a few lines later, the only user is an if() statement that
assigns a variable either to "now" or to ts->idle_lastupdate,
which has the value of "now" at that point.

Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Rik van Riel <riel@...hat.com>
---

 include/linux/tick.h     |    1 -
 kernel/time/tick-sched.c |    5 +----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff -puN include/linux/tick.h~sched-eliminate-the-ts-idle_lastupdate-field include/linux/tick.h
--- a/include/linux/tick.h~sched-eliminate-the-ts-idle_lastupdate-field
+++ a/include/linux/tick.h
@@ -60,7 +60,6 @@ struct tick_sched {
 	ktime_t				idle_waketime;
 	ktime_t				idle_exittime;
 	ktime_t				idle_sleeptime;
-	ktime_t				idle_lastupdate;
 	ktime_t				sleep_length;
 	unsigned long			last_jiffies;
 	unsigned long			next_jiffies;
diff -puN kernel/time/tick-sched.c~sched-eliminate-the-ts-idle_lastupdate-field kernel/time/tick-sched.c
--- a/kernel/time/tick-sched.c~sched-eliminate-the-ts-idle_lastupdate-field
+++ a/kernel/time/tick-sched.c
@@ -158,16 +158,13 @@ update_ts_time_stats(struct tick_sched *
 {
 	ktime_t delta;
 
-	ts->idle_lastupdate = now;
 	if (ts->idle_active) {
 		delta = ktime_sub(now, ts->idle_entrytime);
 		ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
 		ts->idle_entrytime = now;
 	}
 
-	if (ts->idle_active && last_update_time)
-		*last_update_time = ktime_to_us(ts->idle_lastupdate);
-	else
+	if (last_update_time)
 		*last_update_time = ktime_to_us(now);
 
 }
_
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