* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 17:35 [PATCH] cfs: remove unused 'if' condition checking Wang Xingchao
@ 2011-09-16 5:54 ` Yong Zhang
2011-09-16 7:39 ` Paul Turner
` (2 subsequent siblings)
3 siblings, 0 replies; 9+ messages in thread
From: Yong Zhang @ 2011-09-16 5:54 UTC (permalink / raw)
To: Wang Xingchao; +Cc: linux-kernel, mingo, peterz
On Fri, Sep 16, 2011 at 01:35:52PM -0400, Wang Xingchao wrote:
> nr_running must be more than 1, so remove the checking
>
> Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
The patch looks good. And comments below.
> ---
> 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;
It's better to add some comments to explain why se could not be NULL.
Thanks,
Yong
> + 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
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
Only stand for myself
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 17:35 [PATCH] cfs: remove unused 'if' condition checking Wang Xingchao
2011-09-16 5:54 ` Yong Zhang
@ 2011-09-16 7:39 ` Paul Turner
2011-09-16 7:41 ` Paul Turner
2011-09-16 8:38 ` Peter Zijlstra
3 siblings, 0 replies; 9+ messages in thread
From: Paul Turner @ 2011-09-16 7:39 UTC (permalink / raw)
To: linux-kernel
On 09/16/11 10:35, Wang Xingchao wrote:
Please include a one-line summary such as:
sched: remove extra nr_running check in check_preempt_tick
> nr_running must be more than 1, so remove the checking
>
Sure, reasonable.
Please expand this comment though, e.g.
We already test for nr_running > 1 within entity_tick so there is no
need to recheck it within check_preempt_tick().
> Signed-off-by: Wang Xingchao<xingchao.wang@intel.com>
Reviewed-by: Paul Turner <pjt@google.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)
You've mangled the white space on the less-than.
> 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)
And here.
> + return;
>
> - if (delta> ideal_runtime)
> - resched_task(rq_of(cfs_rq)->curr);
> - }
> + if (delta> ideal_runtime)
Here too.
> + resched_task(rq_of(cfs_rq)->curr);
> }
>
> static void
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 17:35 [PATCH] cfs: remove unused 'if' condition checking Wang Xingchao
2011-09-16 5:54 ` Yong Zhang
2011-09-16 7:39 ` Paul Turner
@ 2011-09-16 7:41 ` Paul Turner
2011-09-16 8:17 ` Yong Zhang
2011-09-16 8:38 ` Peter Zijlstra
3 siblings, 1 reply; 9+ messages in thread
From: Paul Turner @ 2011-09-16 7:41 UTC (permalink / raw)
To: Wang Xingchao; +Cc: linux-kernel, mingo, peterz, yong.zhang0
On 09/16/11 10:35, Wang Xingchao wrote:
Please include a one-line summary such as:
sched: remove extra nr_running check in check_preempt_tick
> nr_running must be more than 1, so remove the checking
>
Sure, reasonable.
Please expand this comment though, e.g.
We already test for nr_running > 1 within entity_tick so there is no
need to recheck it within check_preempt_tick().
> Signed-off-by: Wang Xingchao<xingchao.wang@intel.com>
Reviewed-by: Paul Turner <pjt@google.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)
You've mangled the white space on the less-than.
> 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)
And here.
> + return;
>
> - if (delta> ideal_runtime)
> - resched_task(rq_of(cfs_rq)->curr);
> - }
> + if (delta> ideal_runtime)
Here too.
> + resched_task(rq_of(cfs_rq)->curr);
> }
>
> static void
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 7:41 ` Paul Turner
@ 2011-09-16 8:17 ` Yong Zhang
2011-09-16 8:28 ` Paul Turner
0 siblings, 1 reply; 9+ messages in thread
From: Yong Zhang @ 2011-09-16 8:17 UTC (permalink / raw)
To: Paul Turner; +Cc: Wang Xingchao, linux-kernel, mingo, peterz
On Fri, Sep 16, 2011 at 12:41:07AM -0700, Paul Turner wrote:
> On 09/16/11 10:35, Wang Xingchao wrote:
>
> Please include a one-line summary such as:
> sched: remove extra nr_running check in check_preempt_tick
>
> > nr_running must be more than 1, so remove the checking
> >
>
> Sure, reasonable.
>
> Please expand this comment though, e.g.
> We already test for nr_running > 1 within entity_tick so there is no
> need to recheck it within check_preempt_tick().
>
> > Signed-off-by: Wang Xingchao<xingchao.wang@intel.com>
>
> Reviewed-by: Paul Turner <pjt@google.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)
>
> You've mangled the white space on the less-than.
But it looks ok on my side.
And on LKML: https://lkml.org/lkml/2011/9/16/11
So maybe it's not Xingchao's problem.
Thanks,
Yong
>
> > 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)
>
> And here.
>
> > + return;
> >
> > - if (delta> ideal_runtime)
> > - resched_task(rq_of(cfs_rq)->curr);
> > - }
> > + if (delta> ideal_runtime)
>
> Here too.
>
> > + resched_task(rq_of(cfs_rq)->curr);
> > }
> >
> > static void
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
Only stand for myself
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 8:17 ` Yong Zhang
@ 2011-09-16 8:28 ` Paul Turner
2011-09-16 20:36 ` xingchao
0 siblings, 1 reply; 9+ messages in thread
From: Paul Turner @ 2011-09-16 8:28 UTC (permalink / raw)
To: Yong Zhang; +Cc: Wang Xingchao, linux-kernel, mingo, peterz
>
> But it looks ok on my side.
> And on LKML: https://lkml.org/lkml/2011/9/16/11
>
Yeah looks like my client mangled it -- no idea H-T-F it accomplished that,
Sorry,
- Paul
> So maybe it's not Xingchao's problem.
>
> Thanks,
> Yong
>
>>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 8:28 ` Paul Turner
@ 2011-09-16 20:36 ` xingchao
0 siblings, 0 replies; 9+ messages in thread
From: xingchao @ 2011-09-16 20:36 UTC (permalink / raw)
To: Paul Turner
Cc: Yong Zhang, linux-kernel@vger.kernel.org, mingo@elte.hu,
peterz@infradead.org
On Fri, 16 Sep 2011 16:28:25 +0800
Paul Turner <pjt@google.com> wrote:
> >
> > But it looks ok on my side.
> > And on LKML: https://lkml.org/lkml/2011/9/16/11
> >
>
> Yeah looks like my client mangled it -- no idea H-T-F it accomplished
> that,
>
> Sorry,
>
> - Paul
>
> > So maybe it's not Xingchao's problem.
> >
> > Thanks,
> > Yong
> >
> >>
Thanks Paul, Yong, i will send the V2 patch later.
--xingchao
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 17:35 [PATCH] cfs: remove unused 'if' condition checking Wang Xingchao
` (2 preceding siblings ...)
2011-09-16 7:41 ` Paul Turner
@ 2011-09-16 8:38 ` Peter Zijlstra
2011-09-16 20:40 ` xingchao
3 siblings, 1 reply; 9+ messages in thread
From: Peter Zijlstra @ 2011-09-16 8:38 UTC (permalink / raw)
To: Wang Xingchao; +Cc: linux-kernel, mingo, yong.zhang0, Paul Turner
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
--
1.7.1
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH] cfs: remove unused 'if' condition checking
2011-09-16 8:38 ` Peter Zijlstra
@ 2011-09-16 20:40 ` xingchao
0 siblings, 0 replies; 9+ messages in thread
From: xingchao @ 2011-09-16 20:40 UTC (permalink / raw)
To: Peter Zijlstra
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
yong.zhang0@gmail.com, Paul Turner
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
^ permalink raw reply related [flat|nested] 9+ messages in thread