From: Avi Kivity <avi@exanet.com>
To: Joel Becker <jlbec@evilplan.org>
Cc: Yasushi Saito <ysaito@hpl.hp.com>,
linux-aio@kvack.org, linux-kernel@vger.kernel.org,
suparna@in.ibm.com, Janet Morgan <janetmor@us.ibm.com>
Subject: Re: [PATCH 1/2] aio: add vectored I/O support
Date: Sun, 17 Oct 2004 08:25:33 +0200 [thread overview]
Message-ID: <4172105D.3020707@exanet.com> (raw)
In-Reply-To: <20041017001409.GH17142@parcelfarce.linux.theplanet.co.uk>
Joel Becker wrote:
>>I think what happened was that the number of iocbs submitted (64 iocbs
>>of 4K each) did not merge because the device queue depth was very large;
>>no queuing occured because (I imagine) merging happens while a request
>>is waiting for disk readiness.
>>
>>
>
> Why did you submit 64 iocbs of 4K? Was every page virtually
>discontiguous, or did you arbitrarily decide to create a worst-case?
>
>
The application (a userspace filesystem with its own cache) manages
memory in 4K pages, but can perform much larger I/Os, for example during
readahead and after merging writes. After a very short while memory is
completely fragmented.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2004-10-17 6:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-14 20:10 [PATCH 1/2] aio: add vectored I/O support Yasushi Saito
2004-10-16 3:13 ` Joel Becker
2004-10-16 5:18 ` Avi Kivity
2004-10-16 5:37 ` Joel Becker
2004-10-16 8:43 ` Avi Kivity
2004-10-16 16:28 ` Joel Becker
2004-10-16 17:29 ` Avi Kivity
2004-10-17 0:14 ` Joel Becker
2004-10-17 6:25 ` Avi Kivity [this message]
2004-10-16 12:05 ` William Lee Irwin III
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