linux-kernel - Re: [PATCH 3/3] sched: Disable affine wakeups by default

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Message-Id: <1256457685.7356.3.camel@laptop>
Date:	Sun, 25 Oct 2009 09:01:25 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] sched: Disable affine wakeups by default

On Sat, 2009-10-24 at 13:07 -0700, Arjan van de Ven wrote:
> Subject: sched: Disable affine wakeups by default
> From: Arjan van de Ven <arjan@...ux.intel.com>
> 
> The global affine wakeup scheduler feature sounds nice, but there is a problem
> with this: This is ALSO a per scheduler domain feature already.
> By having the global scheduler feature enabled by default, the scheduler domains
> no longer have the option to opt out.
> 
> There are domains (for example the HT/SMT domain) that have good reason to want
> to opt out of this feature.
> 
> With this patch they can opt out, while all other domains currently default to
> the affine setting anyway.
> 
> Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
> 

Hell no, that'll destroy many workloads. What you could possibly do is
disable it for sched domains that are known to share cache, maybe.

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