From: "Michael S. Tsirkin" <mst@redhat.com>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org
Subject: [Qemu-devel] Re: [RFC] vhost-blk implementation
Date: Tue, 23 Mar 2010 14:39:16 +0200 [thread overview]
Message-ID: <20100323123916.GA24750@redhat.com> (raw)
In-Reply-To: <1269304444.7931.68.camel@badari-desktop>
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
next prev parent reply other threads:[~2010-03-23 12:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-23 0:34 [Qemu-devel] [RFC] vhost-blk implementation Badari Pulavarty
2010-03-23 12:39 ` Michael S. Tsirkin [this message]
2010-03-23 14:47 ` [Qemu-devel] " Badari Pulavarty
2010-03-23 17:57 ` Badari Pulavarty
2010-03-23 18:06 ` Michael S. Tsirkin
2010-03-23 19:55 ` Badari Pulavarty
2010-03-24 9:52 ` Michael S. Tsirkin
2010-03-24 11:23 ` Michael S. Tsirkin
2010-03-24 17:58 ` Badari Pulavarty
2010-03-24 18:28 ` Michael S. Tsirkin
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