linux-kernel - Re: [PATCH 0/5] x86,smp: make ticket spinlock proportional backoff w/ auto tuning

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Date:	Thu, 10 Jan 2013 00:27:23 -0200
From:	Rafael Aquini <aquini@...hat.com>
To:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Cc:	Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
	walken@...gle.com, eric.dumazet@...il.com, lwoodman@...hat.com,
	jeremy@...p.org, Jan Beulich <JBeulich@...ell.com>,
	knoel@...hat.com, chegu_vinod@...com, mingo@...hat.com
Subject: Re: [PATCH 0/5] x86,smp: make ticket spinlock proportional backoff
 w/ auto tuning

On Wed, Jan 09, 2013 at 06:20:35PM +0530, Raghavendra K T wrote:
> I ran kernbench on 32 core (mx3850) machine with 3.8-rc2 base.
> x base_3.8rc2
> + rik_backoff
>     N           Min           Max        Median           Avg        Stddev
> x   8       222.977        231.16       227.735       227.388     3.1512986
> +   8        218.75       232.347      229.1035     228.25425     4.2730225
> No difference proven at 95.0% confidence

I got similar results on smaller systems (1 socket, dual-cores and quad-cores)
when running Rik's latest series, no big difference for good nor for worse,
but I also think Rik's work is meant to address bigger systems with more cores
contending for any given spinlock.


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