* [PATCH] sched/fair: avoid !CONFIG_SMP cpufreq update callbacks when go idle
@ 2016-06-27 7:56 Jisheng Zhang
2016-06-27 8:37 ` Peter Zijlstra
0 siblings, 1 reply; 3+ messages in thread
From: Jisheng Zhang @ 2016-06-27 7:56 UTC (permalink / raw)
To: mingo, peterz, rafael.j.wysocki; +Cc: linux-kernel, Jisheng Zhang
This is to avoid cpufreq update callbacks when we go idle on UP
platforms.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
kernel/sched/fair.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bdcbeea..236ec5b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3121,7 +3121,8 @@ static inline void update_load_avg(struct sched_entity *se, int not_used)
struct cfs_rq *cfs_rq = cfs_rq_of(se);
struct rq *rq = rq_of(cfs_rq);
- cpufreq_trigger_update(rq_clock(rq));
+ if (&rq->cfs == cfs_rq)
+ cpufreq_trigger_update(rq_clock(rq));
}
static inline void
--
2.8.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] sched/fair: avoid !CONFIG_SMP cpufreq update callbacks when go idle
2016-06-27 7:56 [PATCH] sched/fair: avoid !CONFIG_SMP cpufreq update callbacks when go idle Jisheng Zhang
@ 2016-06-27 8:37 ` Peter Zijlstra
2016-06-27 8:43 ` Jisheng Zhang
0 siblings, 1 reply; 3+ messages in thread
From: Peter Zijlstra @ 2016-06-27 8:37 UTC (permalink / raw)
To: Jisheng Zhang; +Cc: mingo, rafael.j.wysocki, linux-kernel
On Mon, Jun 27, 2016 at 03:56:03PM +0800, Jisheng Zhang wrote:
> This is to avoid cpufreq update callbacks when we go idle on UP
> platforms.
How so? the patch only avoids calling the update for (!root) cgroups --
which makes sense, but I'm not seeing how that's related to going idle,
or UP at all.
>
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
> kernel/sched/fair.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index bdcbeea..236ec5b 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3121,7 +3121,8 @@ static inline void update_load_avg(struct sched_entity *se, int not_used)
> struct cfs_rq *cfs_rq = cfs_rq_of(se);
> struct rq *rq = rq_of(cfs_rq);
>
> - cpufreq_trigger_update(rq_clock(rq));
> + if (&rq->cfs == cfs_rq)
> + cpufreq_trigger_update(rq_clock(rq));
> }
>
> static inline void
> --
> 2.8.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] sched/fair: avoid !CONFIG_SMP cpufreq update callbacks when go idle
2016-06-27 8:37 ` Peter Zijlstra
@ 2016-06-27 8:43 ` Jisheng Zhang
0 siblings, 0 replies; 3+ messages in thread
From: Jisheng Zhang @ 2016-06-27 8:43 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: mingo, rafael.j.wysocki, linux-kernel
Dear Peter,
On Mon, 27 Jun 2016 10:37:21 +0200
Peter Zijlstra wrote:
> On Mon, Jun 27, 2016 at 03:56:03PM +0800, Jisheng Zhang wrote:
> > This is to avoid cpufreq update callbacks when we go idle on UP
> > platforms.
>
> How so? the patch only avoids calling the update for (!root) cgroups --
> which makes sense, but I'm not seeing how that's related to going idle,
> or UP at all.
oops, I may mis-understand below comment at cfs_rq_util_change()
* It will not get called when we go idle, because the idle
* thread is a different class (!fair),
I mis-read the comment as:
it's the "&rq->cfs == cfs_rq" check to prevent the calling when go idle.
So the patch still make sense, but I need to update the commit msg?
Thanks,
Jisheng
>
> >
> > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > ---
> > kernel/sched/fair.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index bdcbeea..236ec5b 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -3121,7 +3121,8 @@ static inline void update_load_avg(struct sched_entity *se, int not_used)
> > struct cfs_rq *cfs_rq = cfs_rq_of(se);
> > struct rq *rq = rq_of(cfs_rq);
> >
> > - cpufreq_trigger_update(rq_clock(rq));
> > + if (&rq->cfs == cfs_rq)
> > + cpufreq_trigger_update(rq_clock(rq));
> > }
> >
> > static inline void
> > --
> > 2.8.1
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-06-27 7:56 [PATCH] sched/fair: avoid !CONFIG_SMP cpufreq update callbacks when go idle Jisheng Zhang
2016-06-27 8:37 ` Peter Zijlstra
2016-06-27 8:43 ` Jisheng Zhang
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