From: Jens Axboe <qemu@kernel.dk>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [patch] non-blocking disk IO
Date: Tue, 4 Oct 2005 08:44:17 +0200 [thread overview]
Message-ID: <20051004064415.GF3511@suse.de> (raw)
In-Reply-To: <20051004052451.GJ4612@kalmia.hozed.org>
On Tue, Oct 04 2005, Troy Benjegerdes wrote:
> What we want is to be able to have the guest OS request some DMA
> I/O operation, and have qemu be able to use AIO so that the actual disk
> hardware can dump the data directly in the pages the userspace process
> on the guest OS ends up wanting it in, avoiding several expensive memcopy
> and context switch operations.
That should be easy enough to do already, with or without the
nonblocking patch. Just make sure to open the files O_DIRECT and align
the io buffers and lengths. With a 2.6 host, you can usually get away
with 512-b aligment, on 2.4 you may have to ensure 1k/4k alignment.
--
Jens Axboe
next prev parent reply other threads:[~2005-10-04 6:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-03 6:49 [Qemu-devel] [patch] non-blocking disk IO John Coiner
2005-10-03 7:09 ` Magnus Damm
2005-10-03 9:57 ` Elefterios Stamatogiannakis
2005-10-03 12:58 ` Christian MICHON
2005-10-04 7:17 ` John Coiner
2005-10-04 7:46 ` Christian MICHON
2005-10-04 8:52 ` Elefterios Stamatogiannakis
2005-10-04 9:35 ` Christian MICHON
2005-10-04 11:19 ` Christian MICHON
2005-10-04 12:22 ` Jens Axboe
2005-10-04 13:14 ` John Coiner
2005-10-04 13:20 ` Christian MICHON
2005-10-03 13:58 ` Jens Axboe
2005-10-03 22:29 ` John Coiner
2005-10-04 6:41 ` Jens Axboe
2005-10-04 1:35 ` Troy Benjegerdes
2005-10-04 3:25 ` John Coiner
2005-10-04 3:49 ` Henrik Nordstrom
2005-10-04 5:24 ` Troy Benjegerdes
2005-10-04 6:44 ` Jens Axboe [this message]
2005-10-03 18:33 ` Fabrice Bellard
2005-10-04 20:40 ` Brad Campbell
2005-10-04 23:03 ` John Coiner
2005-10-05 11:27 ` Brad Campbell
2005-10-05 14:28 ` Troy Benjegerdes
2005-11-28 22:41 ` Ryan Rempel
-- strict thread matches above, loose matches on Subject: below --
2005-10-03 12:41 John Coiner
2005-10-04 1:34 ` Troy Benjegerdes
2005-10-04 3:16 ` John Coiner
2005-10-04 14:26 ` Troy Benjegerdes
2005-10-04 22:11 ` John Coiner
2005-10-05 3:17 ` Troy Benjegerdes
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