From: Peter Zijlstra <peterz@infradead.org>
To: Barry Song <21cnbao@gmail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
Borislav Petkov <bp@alien8.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Ben Segall <bsegall@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Guodong Xu <guodong.xu@linaro.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Juri Lelli <juri.lelli@redhat.com>,
"Cc: Len Brown" <lenb@kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
LAK <linux-arm-kernel@lists.infradead.org>,
Linuxarm <linuxarm@huawei.com>,
Mark Rutland <mark.rutland@arm.com>, Mel Gorman <mgorman@suse.de>,
msys.mizuma@gmail.com, "Zengtao (B)" <prime.zeng@hisilicon.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Steven Rostedt <rostedt@goodmis.org>,
Barry Song <song.bao.hua@hisilicon.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Will Deacon <will@kernel.org>, x86 <x86@kernel.org>,
yangyicong <yangyicong@huawei.com>
Subject: Re: [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters
Date: Tue, 5 Oct 2021 10:04:13 +0200 [thread overview]
Message-ID: <20211005080413.GL4323@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CAGsJ_4wvLw=US1ddJr=Jrim1vs-F2hpcQ29LQyqDENd7Fk=ssA@mail.gmail.com>
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.
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next prev parent reply other threads:[~2021-10-05 8:07 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-24 8:51 [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters Barry Song
2021-09-24 8:51 ` [PATCH RESEND 1/3] topology: Represent clusters of CPUs within a die Barry Song
2021-10-05 16:33 ` Valentin Schneider
2021-10-05 20:43 ` Barry Song
2021-10-06 10:50 ` Barry Song
2021-10-06 12:18 ` Peter Zijlstra
2021-10-06 12:50 ` Barry Song
2021-10-06 13:55 ` Peter Zijlstra
2021-10-07 10:30 ` Barry Song
2021-10-07 10:35 ` Peter Zijlstra
2021-10-06 13:49 ` Valentin Schneider
2021-09-24 8:51 ` [PATCH RESEND 2/3] scheduler: Add cluster scheduler level in core and related Kconfig for ARM64 Barry Song
2021-10-05 7:35 ` Peter Zijlstra
2021-10-05 9:01 ` Barry Song
2021-10-05 10:40 ` Peter Zijlstra
2021-09-24 8:51 ` [PATCH RESEND 3/3] scheduler: Add cluster scheduler level for x86 Barry Song
2021-10-01 10:32 ` [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters Barry Song
2021-10-01 10:39 ` Vincent Guittot
2021-10-01 14:57 ` Peter Zijlstra
2021-10-01 23:22 ` Tim Chen
2021-10-02 7:09 ` Barry Song
2021-10-04 22:54 ` Tim Chen
2021-10-05 7:54 ` Peter Zijlstra
2021-10-05 8:04 ` Peter Zijlstra [this message]
2021-10-05 9:06 ` Barry Song
2021-10-05 7:50 ` Peter Zijlstra
2021-10-05 9:15 ` Barry Song
2021-10-05 10:58 ` Peter Zijlstra
2021-10-05 13:42 ` Valentin Schneider
2021-10-05 13:50 ` Valentin Schneider
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