From: Andrew Morton <akpm@osdl.org>
To: David Chinner <dgc@sgi.com>
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>
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
Date: Tue, 30 Jan 2007 17:11:32 -0800 [thread overview]
Message-ID: <20070130171132.7be3b054.akpm@osdl.org> (raw)
In-Reply-To: <20070131004436.GS44411608@melbourne.sgi.com>
On Wed, 31 Jan 2007 11:44:36 +1100
David Chinner <dgc@sgi.com> wrote:
> 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?
>
Yup. Even better, use clear_highpage().
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next prev parent reply other threads:[~2007-01-31 1:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-28 14:11 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
2007-01-31 1:11 ` Andrew Morton [this message]
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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