From: Stefan Hajnoczi <stefanha@gmail.com>
To: Asias He <asias@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-aio@kvack.org,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
Benjamin LaHaise <bcrl@kvack.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 0/5] Add vhost-blk support
Date: Mon, 16 Jul 2012 12:58:21 +0100 [thread overview]
Message-ID: <CAJSP0QWgmXns89se+xdGgM6i1_hsfVWPQ8caHua9d-dDA4CTDQ@mail.gmail.com> (raw)
In-Reply-To: <1342107302-28116-1-git-send-email-asias@redhat.com>
On Thu, Jul 12, 2012 at 4:35 PM, Asias He <asias@redhat.com> wrote:
> This patchset adds vhost-blk support. vhost-blk is a in kernel virito-blk
> device accelerator. Compared to userspace virtio-blk implementation, vhost-blk
> gives about 5% to 15% performance improvement.
Why is it 5-15% faster? vhost-blk and the userspace virtio-blk you
benchmarked should be doing basically the same thing:
1. An eventfd file descriptor is signalled when the vring has new
requests available from the guest.
2. A thread wakes up and processes the virtqueue.
3. Linux AIO is used to issue host I/O.
4. An interrupt is injected into the guest.
Does the vhost-blk implementation do anything fundamentally different
from userspace? Where is the overhead that userspace virtio-blk has?
I'm asking because it would be beneficial to fix the overhead
(especially it that could speed up all userspace applications) instead
of adding a special-purpose kernel module to work around the overhead.
Stefan
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next prev parent reply other threads:[~2012-07-16 11:58 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-12 15:35 [PATCH 0/5] Add vhost-blk support Asias He
2012-07-12 15:35 ` [PATCH 1/5] aio: Export symbols and struct kiocb_batch for in kernel aio usage Asias He
2012-07-12 17:50 ` James Bottomley
2012-07-13 1:40 ` Asias He
2012-07-12 16:06 ` [PATCH 0/5] Add vhost-blk support Jeff Moyer
2012-07-13 1:19 ` Asias He
2012-07-16 11:58 ` Stefan Hajnoczi [this message]
2012-07-17 8:29 ` Asias He
2012-07-17 8:52 ` Paolo Bonzini
2012-07-17 9:21 ` Asias He
2012-07-17 9:32 ` Paolo Bonzini
2012-07-17 9:51 ` Michael S. Tsirkin
2012-07-17 11:11 ` Stefan Hajnoczi
2012-07-17 11:26 ` Michael S. Tsirkin
2012-07-17 11:42 ` Stefan Hajnoczi
2012-07-17 11:51 ` Stefan Hajnoczi
2012-07-17 11:54 ` Michael S. Tsirkin
2012-07-17 12:03 ` Stefan Hajnoczi
2012-07-17 12:48 ` Michael S. Tsirkin
2012-07-17 13:02 ` Paolo Bonzini
2012-07-17 13:26 ` Michael S. Tsirkin
2012-07-18 8:47 ` Asias He
2012-07-18 8:12 ` Asias He
2012-07-18 8:26 ` Stefan Hajnoczi
2012-07-18 9:46 ` Ronen Hod
2012-07-17 9:45 ` Michael S. Tsirkin
2012-07-17 10:14 ` Paolo Bonzini
2012-07-17 10:49 ` Michael S. Tsirkin
2012-07-17 10:56 ` Paolo Bonzini
2012-07-17 11:09 ` Michael S. Tsirkin
2012-07-17 11:36 ` Stefan Hajnoczi
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