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Message-ID: <4575087C.6050906@yahoo.com.au>
Date: Tue, 05 Dec 2006 16:49:48 +1100
From: Nick Piggin <nickpiggin@...oo.com.au>
To: Paul Mackerras <paulus@...ba.org>
CC: Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org
Subject: Re: -mm merge plans for 2.6.20
Paul Mackerras wrote:
> Andrew Morton writes:
>>radix-tree-rcu-lockless-readside.patch
>>
>> There's no reason to merge this yet.
>
>
> We want to use it in some powerpc arch code. Currently we use a
> per-cpu array of spinlocks, and this patch would let us get rid of
> that array.
I'd like to get another patch in here before going upstream if possible.
It is not a correctness fix, but it is a bit of a rework.
I also wouldn't mind getting the readahead path, if not the full
pagecache readside, out from under tree_lock in -mm kernels to exercise
the radix-tree concurrency a bit more.
It's just been painfully slow, recently because of these more important
buffered write vs deadlock and pagefault vs invalidate problems that
I've been working on. I don't feel I can load up -mm with too much
unrelated stuff that messes with mm/pagecache internals.
I guess the per-cpu spinlocks are pretty reasonable for scalability,
and you are mainly looking to eliminate the lock/unlock cost in your
interrupt path?
Nick
--
SUSE Labs, Novell Inc.
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