From: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
To: Andrew Morton <akpm@osdl.org>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
mingo@elte.hu, nickpiggin@yahoo.com.au, ak@suse.de,
linux-kernel@vger.kernel.org, rohit.seth@intel.com,
asit.k.mallick@intel.com
Subject: Re: [Patch] sched: new sched domain for representing multi-core
Date: Tue, 31 Jan 2006 18:52:09 -0800 [thread overview]
Message-ID: <20060131185209.B32626@unix-os.sc.intel.com> (raw)
In-Reply-To: <20060131182136.665c8fe3.akpm@osdl.org>; from akpm@osdl.org on Tue, Jan 31, 2006 at 06:21:36PM -0800
On Tue, Jan 31, 2006 at 06:21:36PM -0800, Andrew Morton wrote:
> I was assuming that the code really does something like:
>
> #ifdef CONFIG_SCHED_MC
> some_global_thing = <expr>
> #endif
> #ifdef CONFIG_SCHED_SMT
> some_global_thing = <expr>
> #endif
> }
> ...
> #ifdef CONFIG_SCHED_SMT
> some_other_global_thing = <expr>
> #endif
> #ifdef CONFIG_SCHED_MC
> some_other_global_thing = <expr>
> #endif
>
> Which, looking a bit closer, was wrong (yes?)
yes.
>
> It is a bit irregular that in one place we do the SMT processing first and
> in another we do the MC processing first, but I guess it'll work OK.
yes. It will work Ok.
> We do need to be super-careful in the reviewing and testing here. If we
> slip up we won't have a nice crash to tell us. Instead we'll find that
> some machines with some configs will, under some workloads, take a few
> percent longer than they should. We could waste people's time for years
> until some developer stumbles across something.
I have done testing with specJBB, kernel-compilation, specrate and we are
doing some testing with database workload.. I will also request our
perf team to take a stab at this.
BTW, can you also apply this experimental only patch to -mm.
--
test patch for -mm.. enable CONFIG_SCHED_MC by default in Kconfig.
on systems with no shared caches between cores, this
should help validate domain setup and degeneration code..
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
--- linux-2.6.16-rc1/arch/i386/Kconfig 2006-01-31 16:41:38.019406000 -0800
+++ linux-core/arch/i386/Kconfig 2006-01-31 17:35:50.745916408 -0800
@@ -238,6 +238,7 @@ config SCHED_SMT
config SCHED_MC
bool "Multi-core scheduler support"
depends on SMP
+ default y
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
--- linux-2.6.16-rc1/arch/x86_64/Kconfig 2006-01-31 16:41:38.021405696 -0800
+++ linux-core/arch/x86_64/Kconfig 2006-01-31 17:35:20.640493128 -0800
@@ -249,6 +249,7 @@ config SCHED_SMT
config SCHED_MC
bool "Multi-core scheduler support"
depends on SMP
+ default y
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
next prev parent reply other threads:[~2006-02-01 2:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-26 9:51 [Patch] sched: new sched domain for representing multi-core Siddha, Suresh B
2006-01-27 0:08 ` Ingo Molnar
2006-01-27 3:51 ` Siddha, Suresh B
2006-01-28 0:00 ` Andrew Morton
2006-01-31 1:28 ` Siddha, Suresh B
2006-02-01 1:12 ` Andrew Morton
2006-02-01 1:48 ` Siddha, Suresh B
2006-02-01 2:21 ` Andrew Morton
2006-02-01 2:52 ` Siddha, Suresh B [this message]
2006-01-27 4:42 ` Andi Kleen
2006-01-28 1:45 ` Siddha, Suresh B
2006-01-29 16:56 ` Pavel Machek
2006-01-31 1:31 ` Siddha, Suresh B
-- strict thread matches above, loose matches on Subject: below --
2006-02-09 9:59 Samuel Thibault
2006-02-11 0:51 ` Siddha, Suresh B
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