[PATCH] sched/rt: Remove redundant nr_cpus_allowed test

[PATCH] sched/rt: Remove redundant nr_cpus_allowed test

[Shawn Bohrer]

From: Shawn Bohrer <sbohrer@rgmadvisors.com>

In 76854c7e8f3f4172fef091e78d88b3b751463ac6 "sched: Use
rt.nr_cpus_allowed to recover select_task_rq() cycles" an optimization
was added to select_task_rq_rt() that immediately returns when
p->nr_cpus_allowed == 1 at the beginning of the function.  This makes
the latter p->nr_cpus_allowed > 1 check redundant and can be removed.

Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
---
 kernel/sched/rt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 01970c8..ceebfba 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1213,8 +1213,7 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
 	 */
 	if (curr && unlikely(rt_task(curr)) &&
 	    (curr->nr_cpus_allowed < 2 ||
-	     curr->prio <= p->prio) &&
-	    (p->nr_cpus_allowed > 1)) {
+	     curr->prio <= p->prio)) {
 		int target = find_lowest_rq(p);
 
 		if (target != -1)
-- 
1.8.1.4

Re: [PATCH] sched/rt: Remove redundant nr_cpus_allowed test

[Steven Rostedt]

On Fri,  4 Oct 2013 14:24:53 -0500
Shawn Bohrer <shawn.bohrer@gmail.com> wrote:

> From: Shawn Bohrer <sbohrer@rgmadvisors.com>
> 
> In 76854c7e8f3f4172fef091e78d88b3b751463ac6 "sched: Use
> rt.nr_cpus_allowed to recover select_task_rq() cycles" an optimization
> was added to select_task_rq_rt() that immediately returns when
> p->nr_cpus_allowed == 1 at the beginning of the function.  This makes
> the latter p->nr_cpus_allowed > 1 check redundant and can be removed.
> 
> Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>

Reviewed-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> ---
>  kernel/sched/rt.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 01970c8..ceebfba 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1213,8 +1213,7 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
>  	 */
>  	if (curr && unlikely(rt_task(curr)) &&
>  	    (curr->nr_cpus_allowed < 2 ||
> -	     curr->prio <= p->prio) &&
> -	    (p->nr_cpus_allowed > 1)) {
> +	     curr->prio <= p->prio)) {
>  		int target = find_lowest_rq(p);
>  
>  		if (target != -1)

[tip:sched/core] sched/rt: Remove redundant nr_cpus_allowed test

[tip-bot for Shawn Bohrer]

Commit-ID:  6bfa687c19b7ab8adee03f0d43c197c2945dd869
Gitweb:     http://git.kernel.org/tip/6bfa687c19b7ab8adee03f0d43c197c2945dd869
Author:     Shawn Bohrer <sbohrer@rgmadvisors.com>
AuthorDate: Fri, 4 Oct 2013 14:24:53 -0500
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 6 Oct 2013 11:28:40 +0200

sched/rt: Remove redundant nr_cpus_allowed test

In 76854c7e8f3f4172fef091e78d88b3b751463ac6 ("sched: Use
rt.nr_cpus_allowed to recover select_task_rq() cycles") an
optimization was added to select_task_rq_rt() that immediately
returns when p->nr_cpus_allowed == 1 at the beginning of the
function.

This makes the latter p->nr_cpus_allowed > 1 check redundant,
which can now be removed.

Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: tomk@rgmadvisors.com
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1380914693-24634-1-git-send-email-shawn.bohrer@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/rt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 01970c8..ceebfba 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1213,8 +1213,7 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
 	 */
 	if (curr && unlikely(rt_task(curr)) &&
 	    (curr->nr_cpus_allowed < 2 ||
-	     curr->prio <= p->prio) &&
-	    (p->nr_cpus_allowed > 1)) {
+	     curr->prio <= p->prio)) {
 		int target = find_lowest_rq(p);
 
 		if (target != -1)