linux-kernel - Re: hackbench regression due to commit 9dfc6e68bfe6e

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Message-ID: <alpine.DEB.2.00.1004050853300.23149@router.home>
Date:	Mon, 5 Apr 2010 08:54:49 -0500 (CDT)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
cc:	alex.shi@...el.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Ma, Ling" <ling.ma@...el.com>,
	"Chen, Tim C" <tim.c.chen@...el.com>, Tim C <tim.c.chen@...el.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: hackbench regression due to commit 9dfc6e68bfe6e

On Fri, 2 Apr 2010, Zhang, Yanmin wrote:

> My testing command on my 2 socket machine:
> #hackbench 100 process 20000
>
> With 2.6.33, it takes for about 96 seconds while 2.6.34-rc2 (or the latest tip tree)
> takes for about 101 seconds.
>
> perf shows some functions around SLUB have more cpu utilization, while some other
> SLUB functions have less cpu utilization.

Hmnmmm... The dynamic percpu areas use page tables and that data is used
in the fast path. Maybe the high thread count causes tlb trashing?

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