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[Qemu-devel] Re: [RFC] vhost-blk implementation
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [RFC] vhost-blk implementation |
Date: |
Tue, 23 Mar 2010 14:39:16 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Mon, Mar 22, 2010 at 05:34:04PM -0700, Badari Pulavarty wrote:
> Write Results:
> ==============
>
> I see degraded IO performance when doing sequential IO write
> tests with vhost-blk compared to virtio-blk.
>
> # time dd of=/dev/vda if=/dev/zero bs=2M oflag=direct
>
> I get ~110MB/sec with virtio-blk, but I get only ~60MB/sec with
> vhost-blk. Wondering why ?
Try to look and number of interrupts and/or number of exits.
It could also be that you are overrunning some queue.
I don't see any exit mitigation strategy in your patch:
when there are already lots of requests in a queue, it's usually
a good idea to disable notifications and poll the
queue as requests complete. That could help performance.
--
MST
- [Qemu-devel] [RFC] vhost-blk implementation, Badari Pulavarty, 2010/03/23
- [Qemu-devel] Re: [RFC] vhost-blk implementation,
Michael S. Tsirkin <=
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Badari Pulavarty, 2010/03/23
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Badari Pulavarty, 2010/03/23
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Michael S. Tsirkin, 2010/03/23
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Badari Pulavarty, 2010/03/23
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Michael S. Tsirkin, 2010/03/24
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Michael S. Tsirkin, 2010/03/24
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Badari Pulavarty, 2010/03/24
- [Qemu-devel] Re: [RFC] vhost-blk implementation, Michael S. Tsirkin, 2010/03/24