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Date: Wed, 20 Mar 2002 18:15:10 +0000 (GMT)
From: Hugh Dickins <hugh@veritas.com>
To: "Martin J. Bligh" <Martin.Bligh@us.ibm.com>
cc: Andrea Arcangeli <andrea@suse.de>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Scalability problem (kmap_lock) with -aa kernels
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My guess: persistent kmaps are okay, kmapped high pagetables are okay,
persistent kmapped high pagetables are okay.  What's wrong is how we
flush_all_zero_pkmaps on all cpus, synchronously while holding the
kmap_lock everyone needs to get a new kmap (and hopefully more often,
just inc or dec the pkmap_count of kmap already got).  That's what
cries out for redesign: it's served us well but should now be improved.

Hugh

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