From: Jamie Lokier <jamie@shareable.org>
To: qemu-devel@nongnu.org
Cc: "R. Armiento" <reply-2006@armiento.net>
Subject: Re: [Qemu-devel] add 'monitor' and 'mwait' instruction (update)
Date: Sun, 9 Jul 2006 16:25:04 +0100 [thread overview]
Message-ID: <20060709152504.GC31080@mail.shareable.org> (raw)
In-Reply-To: <200607091230.24239.paul@codesourcery.com>
Paul Brook wrote:
> qemu hardware does support DMA, but I don't think this matters.
> By my reading DMA writes don't need to wake mwait.
> The exact wording is "store operation", which I'd expect to mean
> execution of a store instruction (by a different CPU).
Hmm. x86 CPUs snoop writes by DMA as well as other CPUs, and I'd
expect write snooping to be the mechanism used by 'mwait'.
It would be good to test on a real system whether DMA wakes 'mwait'.
I wouldn't expect many OSes to use this, but I have seen tuned
networking OSes which would benefit from 'mwait' on a network DMA ring
descriptor.
-- Jamie
next prev parent reply other threads:[~2006-07-09 15:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-06 15:13 [Qemu-devel] Pentium D with guest Ubuntu 6.06 server kernel panic with kqemu R. Armiento
2006-07-07 9:06 ` Joachim Henke
2006-07-07 9:39 ` Jens Axboe
2006-07-07 13:39 ` R. Armiento
2006-07-07 12:30 ` [Qemu-devel] [PATCH] add 'monitor' and 'mwait' instruction Joachim Henke
2006-07-07 12:57 ` maestro
2006-07-07 13:22 ` Joachim Henke
2006-07-07 15:21 ` Joachim Henke
2006-07-07 13:18 ` [Qemu-devel] [PATCH] add 'monitor' and 'mwait' instruction (update) Joachim Henke
2006-07-07 13:20 ` Joachim Henke
2006-07-08 13:16 ` R. Armiento
2006-07-08 15:01 ` [Qemu-devel] " Joachim Henke
2006-07-08 20:50 ` R. Armiento
2006-07-09 8:54 ` Joachim Henke
2006-07-09 13:20 ` R. Armiento
2006-07-09 11:30 ` Paul Brook
2006-07-09 15:25 ` Jamie Lokier [this message]
2006-07-09 13:03 ` [Qemu-devel] 'monitor' and 'mwait' instruction Joachim Henke
2006-07-09 15:21 ` [Qemu-devel] add 'monitor' and 'mwait' instruction (update) Jamie Lokier
2006-07-09 15:11 ` Jamie Lokier
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