From: "Stephen C. Tweedie" <sct@redhat.com>
To: Daniel Phillips <phillips@innominate.de>
Cc: "Stephen C. Tweedie" <sct@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: inode->i_dirty_buffers redundant ?
Date: Fri, 26 Jan 2001 11:35:07 +0000 [thread overview]
Message-ID: <20010126113507.J11607@redhat.com> (raw)
In-Reply-To: <200101251047.QAA16434@vxindia.veritas.com> <20010125164432.A12984@redhat.com> <3A708722.C21EC12A@innominate.de>
In-Reply-To: <3A708722.C21EC12A@innominate.de>; from phillips@innominate.de on Thu, Jan 25, 2001 at 09:05:54PM +0100
Hi,
On Thu, Jan 25, 2001 at 09:05:54PM +0100, Daniel Phillips wrote:
> "Stephen C. Tweedie" wrote:
> > We also maintain the
> > per-page buffer lists as caches of the virtual-to-physical mapping to
> > avoid redundant bmap()ping.
>
> Could you clarify that one, please?
The buffer contains a physical label for the block's location on disk.
The page cache is indexed purely by logical location, so doing IO
to/from the page cache requires us to lookup the physical locations of
each block within the page.
Caching the buffer_heads for page cache pages means that once those
lookups are done once, further IO on the same page can bypass the
lookup and go straight to disk.
--Stephen
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next prev parent reply other threads:[~2001-01-26 11:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-25 10:47 inode->i_dirty_buffers redundant ? V Ganesh
2001-01-25 16:44 ` Stephen C. Tweedie
2001-01-25 20:05 ` Daniel Phillips
2001-01-25 21:30 ` Marcelo Tosatti
2001-01-26 11:35 ` Stephen C. Tweedie [this message]
2001-01-26 19:05 ` Daniel Phillips
2001-01-25 21:11 ` Marcelo Tosatti
2001-01-26 17:34 ` Stephen C. Tweedie
-- strict thread matches above, loose matches on Subject: below --
2001-01-26 9:13 V Ganesh
2001-01-24 9:55 V Ganesh
2001-01-24 9:09 ` Marcelo Tosatti
2001-01-24 11:26 ` Stephen C. Tweedie
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