From: David Chinner <dgc@sgi.com>
To: Andrew Morton <akpm@osdl.org>
Cc: "Martin J. Bligh" <mbligh@mbligh.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@elte.hu>, David Chinner <dgc@sgi.com>
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
Date: Wed, 31 Jan 2007 11:44:36 +1100 [thread overview]
Message-ID: <20070131004436.GS44411608@melbourne.sgi.com> (raw)
In-Reply-To: <20070129181557.d4d17dd0.akpm@osdl.org>
On Mon, Jan 29, 2007 at 06:15:57PM -0800, Andrew Morton wrote:
> We still don't know what is the source of kmap() activity which
> necessitated this patch btw. AFAIK the busiest source is ext2 directories,
> but perhaps NFS under certain conditions?
>
> <looks at xfs_iozero>
>
> ->prepare_write no longer requires that the caller kmap the page.
Agreed, but don't we (xfs_iozero) have to map it first to zero it?
I think what you are saying here, Andrew, is that we can
do something like:
page = grab_cache_page
->prepare_write(page)
kaddr = kmap_atomic(page, KM_USER0)
memset(kaddr+offset, 0, bytes)
flush_dcache_page(page)
kunmap_atomic(kaddr, KM_USER0)
->commit_write(page)
to avoid using kmap() altogether?
Cheers,
Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
next prev parent reply other threads:[~2007-01-31 0:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-28 14:11 [PATCH] mm: remove global locks from mm/highmem.c Peter Zijlstra
2007-01-28 14:49 ` Christoph Hellwig
2007-01-28 15:17 ` Ingo Molnar
2007-01-28 15:28 ` Christoph Hellwig
2007-01-28 15:48 ` Ingo Molnar
2007-01-28 15:54 ` Christoph Hellwig
2007-01-28 18:19 ` Ingo Molnar
2007-01-28 22:29 ` Andrew Morton
2007-01-29 2:52 ` Nick Piggin
2007-01-29 9:44 ` Peter Zijlstra
2007-01-30 1:31 ` Martin J. Bligh
2007-01-30 1:41 ` Andrew Morton
2007-01-30 1:49 ` Martin J. Bligh
2007-01-30 2:15 ` Andrew Morton
2007-01-31 0:44 ` David Chinner [this message]
2007-01-31 1:11 ` Andrew Morton
2007-01-31 3:22 ` David Chinner
2007-02-02 12:05 ` Christoph Hellwig
2007-02-02 19:24 ` Matt Mackall
2007-02-02 23:16 ` David Chinner
2007-02-02 23:14 ` David Chinner
2007-01-29 19:08 ` Ingo Molnar
2007-01-29 19:19 ` Hugh Dickins
2007-01-29 19:53 ` Ingo Molnar
2007-01-29 20:06 ` Ingo Molnar
2007-01-30 2:02 ` Nick Piggin
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