From: Andrew Morton <akpm@linux-foundation.org>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: James Bottomley <James.Bottomley@suse.de>,
Catalin Marinas <catalin.marinas@arm.com>,
David Miller <davem@davemloft.net>,
jeff@garzik.org, linux-ide@vger.kernel.org, stable@kernel.org,
tj@kernel.org
Subject: Re: [patch for 2.6.33? 1/1] ata: call flush_dcache_page() around PIO data transfers in libata-aff.c
Date: Wed, 3 Feb 2010 09:06:31 -0800 [thread overview]
Message-ID: <20100203090631.44753f3b.akpm@linux-foundation.org> (raw)
In-Reply-To: <4B69ABCA.1030507@pobox.com>
On Wed, 03 Feb 2010 12:00:58 -0500 Jeff Garzik <jgarzik@pobox.com> wrote:
> On 02/03/2010 11:40 AM, James Bottomley wrote:
> > The fix to libata looks to be just that it should kmap all the time
> > rather than trying to fiddle with the page to see if its higmem. For
> > kmap on a normal page, we should just return the offset map address and
> > do all the flushing.
>
> libata tests PageHighMem() because it was measurably faster to do things
> the current way (which includes local_irq_save/restore, only for
> highmem) on boxes where it actually matters.
>
> It seems more efficient to add a flush where necessary, than
> unconditionally punish everyone...
kmap_atomic() tests PageHighMem() too - it's pretty lightweight for
lowmem pages.
Anyway, I'd draw your attention to this claim in the changelog: "This
patch allows the ARM boards to use a rootfs on CompactFlash with the
PATA platform driver." Immediate-term, we should be looking for a small
fix for this issue which is acceptable for 2.6.33 and 2.6.32 and earlier.
next prev parent reply other threads:[~2010-02-03 17:08 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-02 22:11 [patch for 2.6.33? 1/1] ata: call flush_dcache_page() around PIO data transfers in libata-aff.c akpm
2010-02-02 22:58 ` James Bottomley
2010-02-02 23:05 ` Andrew Morton
2010-02-02 23:14 ` Jeff Garzik
2010-02-02 23:21 ` James Bottomley
2010-02-02 23:21 ` David Miller
2010-02-02 23:30 ` Alan Cox
2010-02-02 23:32 ` James Bottomley
2010-02-02 23:39 ` David Miller
2010-02-03 10:18 ` Catalin Marinas
2010-02-03 16:40 ` James Bottomley
2010-02-03 17:00 ` Jeff Garzik
2010-02-03 17:06 ` Andrew Morton [this message]
2010-02-03 17:15 ` Jeff Garzik
2010-02-03 17:20 ` Andrew Morton
2010-02-03 17:29 ` Jeff Garzik
2010-02-03 17:39 ` James Bottomley
2010-02-04 14:33 ` Catalin Marinas
2010-02-04 15:01 ` James Bottomley
2010-02-04 15:39 ` Catalin Marinas
2010-02-04 21:36 ` James Bottomley
2010-02-03 17:40 ` Alan Cox
2010-02-03 17:46 ` Alan Cox
2010-02-03 17:52 ` Jeff Garzik
2010-02-03 18:00 ` Alan Cox
2010-02-03 18:12 ` Jeff Garzik
2010-02-03 17:49 ` Catalin Marinas
2010-02-03 17:54 ` Jeff Garzik
2010-02-03 17:09 ` David Miller
2010-02-02 23:14 ` James Bottomley
2010-02-03 10:07 ` Catalin Marinas
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