linux-kernel - Re: PATCH] cpuidle: A new variant of the menu governor to boost IO performance

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Message-ID: <20090911163733.GL14984@kernel.dk>
Date:	Fri, 11 Sep 2009 18:37:34 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	linux-kernel@...r.kernel.org, lenb@...nel.org, mingo@...e.hu,
	akpm@...ux-foundation.org, peterz@...radead.org,
	yanmin_zhang@...ux.intel.com, torvalds@...ux-foundation.org
Subject: Re: PATCH] cpuidle: A new variant of the menu governor to boost IO
	performance

On Fri, Sep 11 2009, Arjan van de Ven wrote:
> From: Arjan van de Ven <arjan@...ux.intel.com>
> Subject: [PATCH] cpuidle: A new variant of the menu governor
> 
> This patch adds a new idle governor which balances power savings,
> energy efficiency and performance impact.
> 
> The reason for a reworked governor is that there have been
> serious performance issues reported with the existing code
> on Nehalem server systems.
> 
> To show this I'm sure Andrew wants to see benchmark results:
> (benchmark is "fio", "no cstates" is using "idle=poll")
> 
> 		no cstates	current linux	new algorithm
> 1 disk		107 Mb/s	85 Mb/s		105 Mb/s
> 2 disks		215 Mb/s	123 Mb/s	209 Mb/s
> 12 disks	590 Mb/s	320 Mb/s	585 Mb/s

Heh that's interesting, I have noticed some oddities that I haven't
pursued further yet. But it was definitely power state related, so I'll
give your patch spin.

-- 
Jens Axboe

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