linux-kernel - Re: tbench regression - Why process scheduler has impact on tbench and why small per-cpu slab (SLUB) cache creates the scenario?

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Date:	Tue, 11 Sep 2007 13:19:30 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Nick Piggin <nickpiggin@...oo.com.au>
cc:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, mingo@...e.hu,
	Mel Gorman <mel@...net.ie>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: tbench regression - Why process scheduler has impact on tbench
 and why small per-cpu slab (SLUB) cache creates the scenario?

On Tue, 11 Sep 2007, Nick Piggin wrote:

> The impression I got at vm meeting was that SLUB was good to go :(

Its not? I have had Intel test this thoroughly and they assured me that it 
is up to SLAB. This particular case is an synthetic tests for a PAGE_SIZE 
alloc and SLUB was not optimized for that case because PAGE_SIZEd 
allocations should be handled by the page allocators. Quicklists were 
introduced for the explicit purpose to get these messy page sized cases 
out of the slab allocators.

> But slab allocations don't really control the macro behaviour of a
> benchmark like that so much. So don't wait until something happens
> with the scheduler, fix it now.

Ok so you are for pushing in the page allocator pass through patch from mm 
into rc6? Isnt it a bit late for such a change? I would think that 2.6.24
is early enough.
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