| Message ID | 1445273749-16778-1-git-send-email-dietmar.eggemann@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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
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.
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 [...]
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.
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
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(+)