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From: Anthony Liguori <anthony@codemonkey.ws>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Asias He <asias@redhat.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH RESEND 5/5] vhost-blk: Add vhost-blk support
Date: Fri, 20 Jul 2012 15:56:19 -0500	[thread overview]
Message-ID: <87obnaup70.fsf@codemonkey.ws> (raw)
In-Reply-To: <20120719130957.GD9303@redhat.com>

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Thu, Jul 19, 2012 at 08:05:42AM -0500, Anthony Liguori wrote:
>> Of course, the million dollar question is why would using AIO in the
>> kernel be faster than using AIO in userspace?
>
> Actually for me a more important question is how does it compare
> with virtio-blk dataplane?

I'm not even asking for a benchmark comparision.  It's the same API
being called from a kernel thread vs. a userspace thread.  Why would
there be a 60% performance difference between the two?  That doesn't
make any sense.

There's got to be a better justification for putting this in the kernel
than just that we can.

I completely understand why Christoph's suggestion of submitting BIOs
directly would be faster.  There's no way to do that in userspace.

Regards,

Anthony Liguori

>
> -- 
> MST

  parent reply	other threads:[~2012-07-20 20:56 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-13  8:55 [PATCH RESEND 0/5] Add vhost-blk support Asias He
2012-07-13  8:55 ` [PATCH RESEND 1/5] aio: Export symbols and struct kiocb_batch for in kernel aio usage Asias He
2012-07-13  8:55 ` [PATCH RESEND 2/5] eventfd: Export symbol eventfd_file_create() Asias He
2012-07-13  8:55 ` [PATCH RESEND 3/5] vhost: Make vhost a separate module Asias He
2012-07-13  8:55 ` [PATCH RESEND 4/5] vhost-net: Use VHOST_NET_FEATURES for vhost-net Asias He
2012-07-13  8:55 ` [PATCH RESEND 5/5] vhost-blk: Add vhost-blk support Asias He
2012-07-17 19:10   ` Jeff Moyer
2012-07-18  1:22     ` Asias He
2012-07-18 14:31       ` Jeff Moyer
2012-07-18 14:45         ` Asias He
2012-07-19 13:05   ` Anthony Liguori
2012-07-19 13:09     ` Michael S. Tsirkin
2012-07-19 13:09     ` Michael S. Tsirkin
2012-07-20 10:31       ` Stefan Hajnoczi
2012-07-20 20:56       ` Anthony Liguori [this message]
2012-07-21  1:07         ` Asias He
2012-07-14  7:49 ` [PATCH RESEND 0/5] " Christoph Hellwig
2012-07-16  9:05   ` Asias He
2012-07-17 15:09 ` Michael S. Tsirkin
2012-07-18  2:09   ` Asias He
2012-07-18 11:42   ` Stefan Hajnoczi
2012-07-20 19:30 ` Michael S. Tsirkin

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