From: Jamie Lokier <jamie@shareable.org>
To: Bryan Henderson <hbryan@us.ibm.com>
Cc: Jeremy Allison <jra@samba.org>,
linux-fsdevel@vger.kernel.org, Matthew Wilcox <matthew@wil.cx>
Subject: Re: Efficient handling of sparse files
Date: Mon, 28 Feb 2005 21:49:56 +0000 [thread overview]
Message-ID: <20050228214956.GA21481@mail.shareable.org> (raw)
In-Reply-To: <OFC7AE5B32.B5951682-ON88256FB6.006DA0E8-88256FB6.006F130D@us.ibm.com>
Bryan Henderson wrote:
> I'd resist any interface that exposes implementation details like that.
> The user program shouldn't know anything about block allocations.
A database or file scanner that must read a lot of data can benefit
from having even a rough idea of the layout of the data on disk.
When you have to scan a lot of data, the performance improvement from
sweeping across a disk in block order can be significant - more so than
trying to schedule lots of asynchronous I/O for the elevator to sort.
But despite this use, ->bmap is not ideal for that type of
optimisation because it does not always correspond to position on the
physical device.
-- Jamie
next prev parent reply other threads:[~2005-02-28 21:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-28 17:41 Efficient handling of sparse files Matthew Wilcox
2005-02-28 17:44 ` Jeremy Allison
2005-02-28 20:13 ` Bryan Henderson
2005-02-28 21:49 ` Jamie Lokier [this message]
2005-03-01 18:37 ` Bryan Henderson
2005-02-28 18:57 ` Szakacsits Szabolcs
2005-02-28 19:55 ` Zach Brown
2005-02-28 20:40 ` Anton Altaparmakov
2005-02-28 20:53 ` Zach Brown
2005-03-01 7:50 ` Anton Altaparmakov
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