Date: Mon, 29 Jan 2007 20:53:07 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Hugh Dickins <hugh@veritas.com>
Cc: Andrew Morton <akpm@osdl.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
Message-ID: <20070129195307.GA24434@elte.hu>
References: <1169993494.10987.23.camel@lappy> <20070128142925.df2f4dce.akpm@osdl.org> <20070129190806.GA14353@elte.hu> <Pine.LNX.4.64.0701291916420.10401@blonde.wat.veritas.com>
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* Hugh Dickins <hugh@veritas.com> wrote:

> > For every 64-bit Fedora box there's more than seven 32-bit boxes. I 
> > think 32-bit is going to live with us far longer than many thought, 
> > so we might as well make it work better. Both HIGHMEM and HIGHPTE is 
> > the default on many distro kernels, which pushes the kmap 
> > infrastructure quite a bit.
> 
> But HIGHPTE uses kmap_atomic (in mainline: does -rt use kmap there?)

The contention i saw was on mainline and in the pagecache uses of 
kmap(). With HIGHPTE i only meant that typically every available highmem 
option is enabled on 32-bit distro kernel rpms, to make it work on as 
wide selection of hardware as possible. Sometimes PAE is split into a 
separate rpm, but mostly there's just one 32-bit kernel.

	Ingo
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