* [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle
@ 2020-11-30 14:40 Mel Gorman
2020-11-30 14:47 ` Vincent Guittot
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Mel Gorman @ 2020-11-30 14:40 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra
Cc: Vincent Guittot, Li, Aubrey, Valentin Schneider, linux-kernel,
Mel Gorman
The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
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 0d54d69ba1a5..d9acd55d309b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6087,10 +6087,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
break;
}
}
- cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
if (idle)
return core;
+
+ cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
}
/*
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle
2020-11-30 14:40 [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle Mel Gorman
@ 2020-11-30 14:47 ` Vincent Guittot
2020-12-01 1:04 ` Li, Aubrey
2020-12-01 11:03 ` Peter Zijlstra
2020-12-03 9:13 ` [tip: sched/core] " tip-bot2 for Mel Gorman
2020-12-11 9:34 ` tip-bot2 for Mel Gorman
2 siblings, 2 replies; 6+ messages in thread
From: Vincent Guittot @ 2020-11-30 14:47 UTC (permalink / raw)
To: Mel Gorman
Cc: Ingo Molnar, Peter Zijlstra, Li, Aubrey, Valentin Schneider,
linux-kernel
On Mon, 30 Nov 2020 at 15:40, Mel Gorman <mgorman@techsingularity.net> wrote:
>
> The clearing of SMT siblings from the SIS mask before checking for an idle
> core is a small but unnecessary cost. Defer the clearing of the siblings
> until the scan moves to the next potential target. The cost of this was
> not measured as it is borderline noise but it should be self-evident.
Good point
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> 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 0d54d69ba1a5..d9acd55d309b 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6087,10 +6087,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
> break;
> }
> }
> - cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
>
> if (idle)
> return core;
> +
> + cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
> }
>
> /*
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle
2020-11-30 14:47 ` Vincent Guittot
@ 2020-12-01 1:04 ` Li, Aubrey
2020-12-01 11:03 ` Peter Zijlstra
1 sibling, 0 replies; 6+ messages in thread
From: Li, Aubrey @ 2020-12-01 1:04 UTC (permalink / raw)
To: Vincent Guittot, Mel Gorman
Cc: Ingo Molnar, Peter Zijlstra, Valentin Schneider, linux-kernel
On 2020/11/30 22:47, Vincent Guittot wrote:
> On Mon, 30 Nov 2020 at 15:40, Mel Gorman <mgorman@techsingularity.net> wrote:
>>
>> The clearing of SMT siblings from the SIS mask before checking for an idle
>> core is a small but unnecessary cost. Defer the clearing of the siblings
>> until the scan moves to the next potential target. The cost of this was
>> not measured as it is borderline noise but it should be self-evident.
>
> Good point
This is more reasonable, thanks Mel.
>
>>
>> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
>
> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
>
>> ---
>> 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 0d54d69ba1a5..d9acd55d309b 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -6087,10 +6087,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
>> break;
>> }
>> }
>> - cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
>>
>> if (idle)
>> return core;
>> +
>> + cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
>> }
>>
>> /*
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle
2020-11-30 14:47 ` Vincent Guittot
2020-12-01 1:04 ` Li, Aubrey
@ 2020-12-01 11:03 ` Peter Zijlstra
1 sibling, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2020-12-01 11:03 UTC (permalink / raw)
To: Vincent Guittot
Cc: Mel Gorman, Ingo Molnar, Li, Aubrey, Valentin Schneider, linux-kernel
On Mon, Nov 30, 2020 at 03:47:01PM +0100, Vincent Guittot wrote:
> On Mon, 30 Nov 2020 at 15:40, Mel Gorman <mgorman@techsingularity.net> wrote:
> >
> > The clearing of SMT siblings from the SIS mask before checking for an idle
> > core is a small but unnecessary cost. Defer the clearing of the siblings
> > until the scan moves to the next potential target. The cost of this was
> > not measured as it is borderline noise but it should be self-evident.
>
> Good point
>
> >
> > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
>
> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Thanks!
^ permalink raw reply [flat|nested] 6+ messages in thread
* [tip: sched/core] sched/fair: Clear SMT siblings after determining the core is not idle
2020-11-30 14:40 [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle Mel Gorman
2020-11-30 14:47 ` Vincent Guittot
@ 2020-12-03 9:13 ` tip-bot2 for Mel Gorman
2020-12-11 9:34 ` tip-bot2 for Mel Gorman
2 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Mel Gorman @ 2020-12-03 9:13 UTC (permalink / raw)
To: linux-tip-commits
Cc: Mel Gorman, Peter Zijlstra (Intel), Vincent Guittot, x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 82b738de57d571cd366d89e75b5fd60f3060852b
Gitweb: https://git.kernel.org/tip/82b738de57d571cd366d89e75b5fd60f3060852b
Author: Mel Gorman <mgorman@techsingularity.net>
AuthorDate: Mon, 30 Nov 2020 14:40:20
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 03 Dec 2020 10:00:36 +01:00
sched/fair: Clear SMT siblings after determining the core is not idle
The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20201130144020.GS3371@techsingularity.net
---
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 f5dceda..efac224 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6086,10 +6086,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
break;
}
}
- cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
if (idle)
return core;
+
+ cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
}
/*
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [tip: sched/core] sched/fair: Clear SMT siblings after determining the core is not idle
2020-11-30 14:40 [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle Mel Gorman
2020-11-30 14:47 ` Vincent Guittot
2020-12-03 9:13 ` [tip: sched/core] " tip-bot2 for Mel Gorman
@ 2020-12-11 9:34 ` tip-bot2 for Mel Gorman
2 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Mel Gorman @ 2020-12-11 9:34 UTC (permalink / raw)
To: linux-tip-commits
Cc: Mel Gorman, Peter Zijlstra (Intel),
Ingo Molnar, Vincent Guittot, x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 13d5a5e9f9b8515da3c04305ae1bb03ab91be7a7
Gitweb: https://git.kernel.org/tip/13d5a5e9f9b8515da3c04305ae1bb03ab91be7a7
Author: Mel Gorman <mgorman@techsingularity.net>
AuthorDate: Mon, 30 Nov 2020 14:40:20
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 11 Dec 2020 10:30:38 +01:00
sched/fair: Clear SMT siblings after determining the core is not idle
The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20201130144020.GS3371@techsingularity.net
---
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 f5dceda..efac224 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6086,10 +6086,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
break;
}
}
- cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
if (idle)
return core;
+
+ cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
}
/*
^ permalink raw reply related [flat|nested] 6+ messages in thread
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2020-11-30 14:40 [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle Mel Gorman
2020-11-30 14:47 ` Vincent Guittot
2020-12-01 1:04 ` Li, Aubrey
2020-12-01 11:03 ` Peter Zijlstra
2020-12-03 9:13 ` [tip: sched/core] " tip-bot2 for Mel Gorman
2020-12-11 9:34 ` tip-bot2 for Mel Gorman
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