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Re: [Qemu-devel] [patch] non-blocking disk IO
From: |
John Coiner |
Subject: |
Re: [Qemu-devel] [patch] non-blocking disk IO |
Date: |
Mon, 03 Oct 2005 18:29:39 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.11) Gecko/20050731 |
Jens Axboe wrote:
> Why not use aio for this instead, seems like a better fit than spawning
a thread per block device? That would still require a thread for
handling completions, but you could easily just use a single completion
thread for all devices for this as it would not need to do any real
work.
Pthreads vs. AIO is an open question.
The pthreads implementation works with all disk image formats, without
modifying any format-specific code. To use AIO, each image format driver
would have to be modified.
QEMU already uses pthreads, therefore using pthreads does not add a new
dependency on the host platform. (Or so I thought. The build on Windows
broke anyway. Haha... my bad...)
My questions are:
* Which QEMU host platforms support Posix AIO?
* Which host platform has the slowest pthreads library, and how many
cycles will it waste on pthreads overhead?
* What is the likely performance benefit of using AIO?
When I have time, I'll hack AIO into the "raw" image driver, and take
some benchmarks on a linux host.
Thanks.
-John
- Re: [Qemu-devel] [patch] non-blocking disk IO, (continued)
- Re: [Qemu-devel] [patch] non-blocking disk IO, Christian MICHON, 2005/10/03
- Re: [Qemu-devel] [patch] non-blocking disk IO, John Coiner, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Christian MICHON, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Elefterios Stamatogiannakis, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Christian MICHON, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Christian MICHON, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Jens Axboe, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, John Coiner, 2005/10/04
- Re: [Qemu-devel] [patch] non-blocking disk IO, Christian MICHON, 2005/10/04
Re: [Qemu-devel] [patch] non-blocking disk IO, Jens Axboe, 2005/10/03
Re: [Qemu-devel] [patch] non-blocking disk IO, John Coiner, 2005/10/03
Re: [Qemu-devel] [patch] non-blocking disk IO, Fabrice Bellard, 2005/10/03
Re: [Qemu-devel] [patch] non-blocking disk IO, Brad Campbell, 2005/10/04