linux-kernel - Re: [PATCH RESEND 5/5] vhost-blk: Add vhost-blk support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87obnaup70.fsf@codemonkey.ws>
Date:	Fri, 20 Jul 2012 15:56:19 -0500
From:	Anthony Liguori <anthony@...emonkey.ws>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Asias He <asias@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH RESEND 5/5] vhost-blk: Add vhost-blk support

"Michael S. Tsirkin" <mst@...hat.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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/