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SubjectRe: [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters
On Tue, Oct 5, 2021 at 9:05 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Sat, Oct 02, 2021 at 08:09:58PM +1300, Barry Song wrote:
>
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 7e4651a1aaf4..86821e83b935 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -993,8 +993,13 @@ config SCHED_CLUSTER
> > bool "Cluster scheduler support"
> > help
> > Cluster scheduler support improves the CPU scheduler's decision
> > + making when dealing with machines that have clusters of CPUs.
> > + Cluster usually means a couple of CPUs which are placed closely
> > + by sharing mid-level caches, last-level cache tags or internal
> > + busses. For example, on Hisilicon Kunpeng920, each 4 CPUs share
> > + LLC cache tags. This feature isn't a universal win because it
> > + can bring a cost of slightly increased overhead in some places.
> > + If unsure say N here.
> >
> > config SCHED_SMT
> > bool "SMT scheduler support"
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index bd27b1cdac34..940eb1fe0abb 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1002,12 +1002,17 @@ config NR_CPUS
> > to the kernel image.
> >
> > config SCHED_CLUSTER
> > + def_bool y
> > + prompt "Cluster scheduler support"
> > help
> > Cluster scheduler support improves the CPU scheduler's decision
> > + making when dealing with machines that have clusters of CPUs.
> > + Cluster usually means a couple of CPUs which are placed closely
> > + by sharing mid-level caches, last-level cache tags or internal
> > + busses. For example, on x86 Jacobsville, each 4 CPUs share one
> > + L2 cache.
>
> This feature isn't a universal win because it can bring
> > + a cost of slightly increased overhead in some places. If unsure
> > + say N here.
>
> That is a really odd addition to a default-y feature.
>
> How about I make both:
>
> help
> Cluster scheduler support improves the CPU scheduler's decision
> making when dealing with machines that have clusters of CPUs.
> Cluster usually means a couple of CPUs which are placed closely
> by sharing mid-level caches, last-level cache tags or internal
> busses.

looks good to me. thanks!

barry

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