linux-kernel - Re: [PATCH] x86: eliminate redundant/contradicting cache line size config options

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Message-ID: <20091123065201.564d4b16@infradead.org>
Date:	Mon, 23 Nov 2009 06:52:01 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Nick Piggin <npiggin@...e.de>, Jan Beulich <JBeulich@...ell.com>,
	tglx@...utronix.de, linux-kernel@...r.kernel.org, hpa@...or.com,
	Ravikiran Thirumalai <kiran@...lex86.org>,
	Shai Fultheim <shai@...lemp.com>
Subject: Re: [PATCH] x86: eliminate redundant/contradicting cache line size
 config options

On Mon, 23 Nov 2009 09:34:59 +0100
Ingo Molnar <mingo@...e.hu> wrote:

> 
> * Arjan van de Ven <arjan@...radead.org> wrote:
> 
> > On Thu, 19 Nov 2009 09:13:07 +0100
> > Nick Piggin <npiggin@...e.de> wrote:
> > > 
> > > My other point was just this, but I don't care too much. But it is
> > > worded pretty negatively. The key here is that increasing the
> > > value too large tends to only cost a very small amount of size
> > > (and no increase in cacheline foot print, only RAM). 
> > 
> > 128 has a pretty significant impact on TPC-C benchmarks.....
> > it was the top issue until mainline fixed it to default to 64
> 
> Mind sending a patch that sets the default to 64 on NUMA too?
> 
> P4 based NUMA boxes are ... a bad memory to be forgotten.

this patch adds a regression. Linux defaulted to 64 since.. march or so.

now we go back to the old setting; Nick should fix that. Or at least
extremely document and justify this change....



-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
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