From: Jamie Lokier <jamie@shareable.org>
To: qemu-devel@nongnu.org
Cc: Anthony Liguori <aliguori@us.ibm.com>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device
Date: Sat, 8 Dec 2007 14:09:06 +0000 [thread overview]
Message-ID: <20071208140906.GA22712@shareable.org> (raw)
In-Reply-To: <200712081322.39762.paul@codesourcery.com>
Paul Brook wrote:
> > virtio makes things a bit trickier though. There's a shared ring queue
> > between the host and guest. The ring queue is lock-less and depends on
> > the ability to atomically increment ring queue indices to be SMP safe.
> > Using a copy-API wouldn't be a problem for QEMU since the host and guest
> > are always running in lock-step. A copy API is actually needed to deal
> > with differing host/guest alignment and endianness.
>
> That seems a rather poor design choice, as many architectures don't have an
> atomic increment instruction. Oh well.
Most have compare-and-swap or load-locked/store-conditional
instructions, though, which can be used to implement atomic increment.
-- Jamie
next prev parent reply other threads:[~2007-12-08 14:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-04 21:54 [Qemu-devel] [PATCH 2/3] virtio network device Anthony Liguori
2007-12-04 22:12 ` Anthony Liguori
2007-12-04 23:49 ` [Qemu-devel] " Dor Laor
2007-12-05 17:18 ` Anthony Liguori
2007-12-05 17:44 ` Paul Brook
2007-12-05 20:20 ` Anthony Liguori
2007-12-06 9:27 ` Jamie Lokier
2007-12-08 13:22 ` Paul Brook
2007-12-08 14:09 ` Jamie Lokier [this message]
2007-12-08 16:45 ` Paul Brook
2007-12-08 19:52 ` Blue Swirl
2007-12-08 21:55 ` Jamie Lokier
2007-12-08 22:02 ` Anthony Liguori
2007-12-12 1:24 ` Rusty Russell
2007-12-12 1:40 ` Anthony Liguori
2007-12-18 2:31 ` Rusty Russell
2007-12-08 21:59 ` Anthony Liguori
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