Date: Thu, 14 Jun 2007 14:32:48 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, hch@infradead.org
Subject: Re: [patch 00/14] Page cache cleanup in anticipation of Large
 Blocksize support
Message-Id: <20070614143248.736312f8.akpm@linux-foundation.org>
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	<20070614130645.cabdff1b.akpm@linux-foundation.org>
	<Pine.LNX.4.64.0706141411180.1579@schroedinger.engr.sgi.com>
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> On Thu, 14 Jun 2007 14:20:04 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> > I think the best way to proceed would be to investigate that _general_
> > optimisation and then, based upon the results of that work, decide whether
> > further _specialised_ changes such as variable PAGE_CACHE_SIZE are needed,
> > and if so, what they should be.
> 
> As has been pointed out performance is only one beneficial issue of
> having a higher page cache. It is doubtful in principle that the proposed 
> alternative can work given that locking overhead and management overhead
> by the VM are not minimized but made more complex by your envisioned 
> solution.

Why do we have to replay all of this?

You: conceptully-new add-on which benefits 0.25% of the user base, provided
they select the right config options and filesystem.

Me: simpler enhancement which benefits 100% of the user base (ie: includes
4k blocksize, 4k pagesize) and which also fixes your performance problem
with that HBA.


We want the 100% case.
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