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SubjectRe: [PATCH] cfs: remove unused 'if' condition checking
On Fri, 16 Sep 2011 16:38:32 +0800
Peter Zijlstra <peterz@infradead.org> wrote:

> Thanks, queued it as:
>
> ---
> Subject: sched: Remove redundant test in check_preempt_tick()
> From: Wang Xingchao <xingchao.wang@intel.com>
> Date: Fri, 16 Sep 2011 13:35:52 -0400
>
> The caller already checks for nr_running > 1, therefore we don't have
> to do so again.
>
> Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
> Reviewed-by: Paul Turner <pjt@google.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Link:
> http://lkml.kernel.org/r/1316194552-12019-1-git-send-email-xingchao.wang@intel.com
> --- kernel/sched_fair.c | 16 ++++++++--------
> 1 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index 1ca2cd4..fef0bfd 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1106,6 +1106,8 @@ static void
> check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> {
> unsigned long ideal_runtime, delta_exec;
> + struct sched_entity *se;
> + s64 delta;
>
> ideal_runtime = sched_slice(cfs_rq, curr);
> delta_exec = curr->sum_exec_runtime -
> curr->prev_sum_exec_runtime; @@ -1127,16 +1129,14 @@
> check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> if (delta_exec < sysctl_sched_min_granularity) return;
>
> - if (cfs_rq->nr_running > 1) {
> - struct sched_entity *se =
> __pick_first_entity(cfs_rq);
> - s64 delta = curr->vruntime - se->vruntime;
> + se = __pick_first_entity(cfs_rq);
> + delta = curr->vruntime - se->vruntime;
>
> - if (delta < 0)
> - return;
> + if (delta < 0)
> + return;
>
> - if (delta > ideal_runtime)
> - resched_task(rq_of(cfs_rq)->curr);
> - }
> + if (delta > ideal_runtime)
> + resched_task(rq_of(cfs_rq)->curr);
> }
>
> static void

oh, so fast Peter, thank you. Then it's no need to take the V2 patch.

--xingchao

From 3192939226ba274b5b9a32f07fc10025bb836ad3 Mon Sep 17 00:00:00 2001
From: Wang Xingchao <xingchao.wang@intel.com>
Date: Mon, 12 Sep 2011 14:30:16 +0800
Subject: [V2 PATCH] sched:remove extra nr_running check in
check_preempt_tick

nr_running must be more than 1, remove the checking.
We already test for nr_running > 1 in entity_tick(),
so it's no need to recheck it within check_preempt_tick().

Reviewed-by: Paul Turner <pjt@google.com>
Reviewed-by: yong.zhang0@gmail.com
Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
---
kernel/sched_fair.c | 16 ++++++++--------
1 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 1ca2cd4..fef0bfd 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1106,6 +1106,8 @@ static void
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
{
unsigned long ideal_runtime, delta_exec;
+ struct sched_entity *se;
+ s64 delta;

ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime -
curr->prev_sum_exec_runtime; @@ -1127,16 +1129,14 @@
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) if
(delta_exec < sysctl_sched_min_granularity) return;

- if (cfs_rq->nr_running > 1) {
- struct sched_entity *se = __pick_first_entity(cfs_rq);
- s64 delta = curr->vruntime - se->vruntime;
+ se = __pick_first_entity(cfs_rq);
+ delta = curr->vruntime - se->vruntime;

- if (delta < 0)
- return;
+ if (delta < 0)
+ return;

- if (delta > ideal_runtime)
- resched_task(rq_of(cfs_rq)->curr);
- }
+ if (delta > ideal_runtime)
+ resched_task(rq_of(cfs_rq)->curr);
}

static void
--
1.7.1

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