* [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-19 16:55 ` Dietmar Eggemann
0 siblings, 0 replies; 10+ messages in thread
From: Dietmar Eggemann @ 2015-10-19 16:55 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-19 16:55 ` Dietmar Eggemann
0 siblings, 0 replies; 10+ messages in thread
From: Dietmar Eggemann @ 2015-10-19 16:55 UTC (permalink / raw)
To: linux-arm-kernel; +Cc: Catalin Marinas, Will Deacon, linux-kernel
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
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH] ARM64: Enable multi-core scheduler support by default
2015-10-19 16:55 ` Dietmar Eggemann
@ 2015-10-28 14:01 ` Punit Agrawal
-1 siblings, 0 replies; 10+ messages in thread
From: Punit Agrawal @ 2015-10-28 14:01 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-28 14:01 ` Punit Agrawal
0 siblings, 0 replies; 10+ messages in thread
From: Punit Agrawal @ 2015-10-28 14:01 UTC (permalink / raw)
To: Will Deacon, Catalin Marinas
Cc: linux-arm-kernel, linux-kernel, dietmar.eggemann
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH] ARM64: Enable multi-core scheduler support by default
2015-10-19 16:55 ` Dietmar Eggemann
@ 2015-10-29 17:19 ` Catalin Marinas
-1 siblings, 0 replies; 10+ messages in thread
From: Catalin Marinas @ 2015-10-29 17:19 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-29 17:19 ` Catalin Marinas
0 siblings, 0 replies; 10+ messages in thread
From: Catalin Marinas @ 2015-10-29 17:19 UTC (permalink / raw)
To: Dietmar Eggemann; +Cc: linux-arm-kernel, Will Deacon, linux-kernel
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH] ARM64: Enable multi-core scheduler support by default
2015-10-29 17:19 ` Catalin Marinas
@ 2015-10-30 12:29 ` Dietmar Eggemann
-1 siblings, 0 replies; 10+ messages in thread
From: Dietmar Eggemann @ 2015-10-30 12:29 UTC (permalink / raw)
To: linux-arm-kernel
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
[...]
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-30 12:29 ` Dietmar Eggemann
0 siblings, 0 replies; 10+ messages in thread
From: Dietmar Eggemann @ 2015-10-30 12:29 UTC (permalink / raw)
To: Catalin Marinas; +Cc: linux-arm-kernel, Will Deacon, linux-kernel
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
[...]
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH] ARM64: Enable multi-core scheduler support by default
2015-10-30 12:29 ` Dietmar Eggemann
@ 2015-10-30 15:35 ` Catalin Marinas
-1 siblings, 0 replies; 10+ messages in thread
From: Catalin Marinas @ 2015-10-30 15:35 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ARM64: Enable multi-core scheduler support by default
@ 2015-10-30 15:35 ` Catalin Marinas
0 siblings, 0 replies; 10+ messages in thread
From: Catalin Marinas @ 2015-10-30 15:35 UTC (permalink / raw)
To: Dietmar Eggemann; +Cc: Will Deacon, linux-kernel, linux-arm-kernel
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
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2015-10-30 15:35 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-10-19 16:55 [PATCH] ARM64: Enable multi-core scheduler support by default Dietmar Eggemann
2015-10-19 16:55 ` Dietmar Eggemann
2015-10-28 14:01 ` Punit Agrawal
2015-10-28 14:01 ` Punit Agrawal
2015-10-29 17:19 ` Catalin Marinas
2015-10-29 17:19 ` Catalin Marinas
2015-10-30 12:29 ` Dietmar Eggemann
2015-10-30 12:29 ` Dietmar Eggemann
2015-10-30 15:35 ` Catalin Marinas
2015-10-30 15:35 ` Catalin Marinas
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.