Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1250929 > unrolled thread

[PATCH] ARM64: Enable multi-core scheduler support by default

Started byDietmar Eggemann <dietmar.eggemann@arm.com>
First post2015-10-19 19:00 +0200
Last post2015-10-30 16:40 +0100
Articles 5 — 3 participants

Back to article view | Back to linux.kernel

Contents

  [PATCH] ARM64: Enable multi-core scheduler support by default Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-10-19 19:00 +0200
    Re: [PATCH] ARM64: Enable multi-core scheduler support by default Punit Agrawal <punit.agrawal@arm.com> - 2015-10-28 15:10 +0100
    Re: [PATCH] ARM64: Enable multi-core scheduler support by default Catalin Marinas <catalin.marinas@arm.com> - 2015-10-29 18:20 +0100
      Re: [PATCH] ARM64: Enable multi-core scheduler support by default Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-10-30 13:30 +0100
        Re: [PATCH] ARM64: Enable multi-core scheduler support by default Catalin Marinas <catalin.marinas@arm.com> - 2015-10-30 16:40 +0100

#1250929 — [PATCH] ARM64: Enable multi-core scheduler support by default

FromDietmar Eggemann <dietmar.eggemann@arm.com>
Date2015-10-19 19:00 +0200
Subject[PATCH] ARM64: Enable multi-core scheduler support by default
Message-ID<qllWW-1T1-33@gated-at.bofh.it>
Make sure that the task scheduler domain hierarchy is set-up correctly
on systems with single or multi-cluster topology.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 34d71dd86781..dc70d715bc38 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -51,6 +51,7 @@ CONFIG_PCI=y
 CONFIG_PCI_MSI=y
 CONFIG_PCI_XGENE=y
 CONFIG_SMP=y
+CONFIG_SCHED_MC=y
 CONFIG_PREEMPT=y
 CONFIG_KSM=y
 CONFIG_TRANSPARENT_HUGEPAGE=y
-- 
1.9.1

--
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/

[toc] | [next] | [standalone]

#1258099

FromPunit Agrawal <punit.agrawal@arm.com>
Date2015-10-28 15:10 +0100
Message-ID<qozAn-3CV-51@gated-at.bofh.it>
In reply to#1250929
Hi Catalin, Will,

Dietmar Eggemann <dietmar.eggemann@arm.com> writes:

> Make sure that the task scheduler domain hierarchy is set-up correctly
> on systems with single or multi-cluster topology.
>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

FWIW,
        Acked-by: Punit Agrawal <punit.agrawal@arm.com>

I am not sure how we update the defconfig. Can you pick this up for 4.4?
Or will this be picked up after the merge window?

Thanks,
Punit

> ---
>  arch/arm64/configs/defconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index 34d71dd86781..dc70d715bc38 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -51,6 +51,7 @@ CONFIG_PCI=y
>  CONFIG_PCI_MSI=y
>  CONFIG_PCI_XGENE=y
>  CONFIG_SMP=y
> +CONFIG_SCHED_MC=y
>  CONFIG_PREEMPT=y
>  CONFIG_KSM=y
>  CONFIG_TRANSPARENT_HUGEPAGE=y
--
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/

[toc] | [prev] | [next] | [standalone]

#1258922

FromCatalin Marinas <catalin.marinas@arm.com>
Date2015-10-29 18:20 +0100
Message-ID<qoZ1M-34X-9@gated-at.bofh.it>
In reply to#1250929
On Mon, Oct 19, 2015 at 05:55:49PM +0100, Dietmar Eggemann wrote:
> Make sure that the task scheduler domain hierarchy is set-up correctly
> on systems with single or multi-cluster topology.
> 
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
> ---
>  arch/arm64/configs/defconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index 34d71dd86781..dc70d715bc38 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -51,6 +51,7 @@ CONFIG_PCI=y
>  CONFIG_PCI_MSI=y
>  CONFIG_PCI_XGENE=y
>  CONFIG_SMP=y
> +CONFIG_SCHED_MC=y
>  CONFIG_PREEMPT=y
>  CONFIG_KSM=y
>  CONFIG_TRANSPARENT_HUGEPAGE=y

Question: does enabling this option have any (positive) effect on the
vanilla kernel or it requires additional patches like EAS?

Thanks.

-- 
Catalin
--
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/

[toc] | [prev] | [next] | [standalone]

#1259469

FromDietmar Eggemann <dietmar.eggemann@arm.com>
Date2015-10-30 13:30 +0100
Message-ID<qpgYG-5KW-27@gated-at.bofh.it>
In reply to#1258922
On 10/29/2015 05:19 PM, Catalin Marinas wrote:
> On Mon, Oct 19, 2015 at 05:55:49PM +0100, Dietmar Eggemann wrote:
>> Make sure that the task scheduler domain hierarchy is set-up correctly
>> on systems with single or multi-cluster topology.
>>
>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
>> ---
>>   arch/arm64/configs/defconfig | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
>> index 34d71dd86781..dc70d715bc38 100644
>> --- a/arch/arm64/configs/defconfig
>> +++ b/arch/arm64/configs/defconfig
>> @@ -51,6 +51,7 @@ CONFIG_PCI=y
>>   CONFIG_PCI_MSI=y
>>   CONFIG_PCI_XGENE=y
>>   CONFIG_SMP=y
>> +CONFIG_SCHED_MC=y
>>   CONFIG_PREEMPT=y
>>   CONFIG_KSM=y
>>   CONFIG_TRANSPARENT_HUGEPAGE=y
>
> Question: does enabling this option have any (positive) effect on the
> vanilla kernel or it requires additional patches like EAS?

It improves the task scheduler decisions on multi-cluster systems. You 
have to iterate over all cpu's less frequently when gathering the sched 
group statistics e.g. during CFS load-balancing.

You essentially replace a flat (all cpus) with an hierarchical approach 
(lowest level: sched group eq. cpu, next level: sched group eq. cluster) 
and do CFS load balancing frequently between two cpu's of the same 
cluster (lowest level) and less frequently between two cpus from 
different cluster.

Not sure that I would see an effect on the performance score on a JUNO 
board when running hackbench. Could give it a try ... Probably easier to 
spot on a machine with >32 logical cpus.

EAS has to work with both approaches although we do all our tests with 
CONFIG_SCHED_MC=y. EAS operates on sched groups so the actual structure 
of the sched domain hierarchy is hidden. (at least in theory).

For me CONFIG_SCHED_MC=y is something I would expect when I evaluate the 
task scheduler on a multi-cluster system.

-- Dietmar

[...]

--
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/

[toc] | [prev] | [next] | [standalone]

#1259586

FromCatalin Marinas <catalin.marinas@arm.com>
Date2015-10-30 16:40 +0100
Message-ID<qpjWy-7ym-27@gated-at.bofh.it>
In reply to#1259469
On Fri, Oct 30, 2015 at 12:29:00PM +0000, Dietmar Eggemann wrote:
> On 10/29/2015 05:19 PM, Catalin Marinas wrote:
> >On Mon, Oct 19, 2015 at 05:55:49PM +0100, Dietmar Eggemann wrote:
> >>Make sure that the task scheduler domain hierarchy is set-up correctly
> >>on systems with single or multi-cluster topology.
> >>
> >>Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
> >>---
> >>  arch/arm64/configs/defconfig | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >>diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> >>index 34d71dd86781..dc70d715bc38 100644
> >>--- a/arch/arm64/configs/defconfig
> >>+++ b/arch/arm64/configs/defconfig
> >>@@ -51,6 +51,7 @@ CONFIG_PCI=y
> >>  CONFIG_PCI_MSI=y
> >>  CONFIG_PCI_XGENE=y
> >>  CONFIG_SMP=y
> >>+CONFIG_SCHED_MC=y
> >>  CONFIG_PREEMPT=y
> >>  CONFIG_KSM=y
> >>  CONFIG_TRANSPARENT_HUGEPAGE=y
> >
> >Question: does enabling this option have any (positive) effect on the
> >vanilla kernel or it requires additional patches like EAS?
> 
> It improves the task scheduler decisions on multi-cluster systems. You have
> to iterate over all cpu's less frequently when gathering the sched group
> statistics e.g. during CFS load-balancing.
> 
> You essentially replace a flat (all cpus) with an hierarchical approach
> (lowest level: sched group eq. cpu, next level: sched group eq. cluster) and
> do CFS load balancing frequently between two cpu's of the same cluster
> (lowest level) and less frequently between two cpus from different cluster.
> 
> Not sure that I would see an effect on the performance score on a JUNO board
> when running hackbench. Could give it a try ... Probably easier to spot on a
> machine with >32 logical cpus.

I did some tests on Juno last week with and without this option and I
haven't noticed any difference.

Anyway, thanks for the explanation. Patch applied.

-- 
Catalin
--
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/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web