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Re: [Qemu-devel] AMD 100% CPU bug; patch available?
From: |
Rick Vernam |
Subject: |
Re: [Qemu-devel] AMD 100% CPU bug; patch available? |
Date: |
Tue, 12 Aug 2008 12:19:24 -0500 |
User-agent: |
KMail/1.9.9 |
I'm not so sure there is such a bug - I've been running qemu on AMD 3700
laptop for years w/o that, or much of any other issue (except once upon a
time an ACPI issue w/ windows guest causing host cpu to peg 100%).
I run gentoo host + various windows/linux guests.
points of interest may (or may not) be details such as host kernel
configuration? qemu version? qemu options used? built yourself or
pre-packaged?
I don't claim to be able to help you solve the problem, but there's not much
here to work with...
On Tuesday 12 August 2008 11:36:08 am David Barrett wrote:
> Can anybody confirm that qemu works on an AMD processor with a Linux
> host and Linux guest (ideally Ubuntu 8.04 in both cases) without using
> 100% CPU? (qemu process on the host uses 100% CPU despite all processes
> on the guest being idle.)
>
> Or is there a known bug that qemu with a Ubuntu guest always uses 100%
> CPU on AMD Ubuntu hosts? If so, is there a patch or workaround for it?
>
> I don't know this for certain, but it's the only pattern I can see: I've
> run qemu on a bunch of laptops and servers over the past 12 months --
> often with the exact same image and exact same commands -- and some
> hosts see the guest VM use limited CPU, and others a solid 100%. This
> seems to be the case whether or not -kernel-kqemu is used.
>
> At first I thought it was an Ubuntu/Fedora Core issue, as I was running
> Ubuntu on laptops and FC4 on servers (and I only saw this problem on
> servers). But I just got a new Ubuntu server and the problem remains.
>
> Now I realize there's another commonality: my servers have been
> AMD-based, whereas laptops were Intel based. With this theory I looked
> through the user forum and saw a strong correlation between reports of
> 100% CPU and AMD processors.
>
> Is this old news or a debunked theory?
>
> Is there some tool like CPUIdle I should be running? Any suggestions
> for how to start debugging the issue?
>
> Thanks!
>
> -david