Subject: Re: SLUB performance regression vs SLAB
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Christoph Lameter <clameter@sgi.com>,
       Matthew Wilcox <willy@linux.intel.com>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Christoph Hellwig <hch@lst.de>,
       Mel Gorman <mel@skynet.ie>, linux-fsdevel@vger.kernel.org,
       linux-kernel@vger.kernel.org, David Chinner <dgc@sgi.com>,
       Jens Axboe <jens.axboe@oracle.com>
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Date: Thu, 04 Oct 2007 20:26:12 +0200
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On Thu, 2007-10-04 at 10:50 -0700, Arjan van de Ven wrote:
> On Thu, 4 Oct 2007 10:38:15 -0700 (PDT)
> Christoph Lameter <clameter@sgi.com> wrote:
> 
> 
> > Yeah the fastpath vs. slow path is not the issue as Siddha and I
> > concluded earlier. Seems that we are mainly seeing cacheline bouncing
> > due to two cpus accessing meta data in the same page struct. The
> > patches in MM that are scheduled to be merged for .24 address 
> 
> 
> Ok every time something says anything not 100% positive about SLUB you
> come back with "but it's fixed in the next patch set"... *every time*.
> 
> To be honest, to me that sounds that SLUB isn't ready for prime time
> yet, or at least not ready to be the only one in town...
> 
> The day that the answer is "the kernel.org slub is fixing all the
> issues" is when it's ready..

Arjan, to be honest, there has been some confusion on _what_ code has
been tested with what results. And with Christoph not able to reproduce
these results locally, it is very hard for him to fix it proper.


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