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Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? |
Date: |
Tue, 3 Aug 2010 13:48:08 +0100 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Tue, Aug 03, 2010 at 03:37:14PM +0300, Gleb Natapov wrote:
> On Tue, Aug 03, 2010 at 01:10:00PM +0100, Richard W.M. Jones wrote:
> > I can't see anything about this in the kernel changelog. Can you
> > point me to the commit or the key phrase to look for?
> >
> 7972995b0c346de76
Thanks - I see.
> > Also, what's the point of making in/out "more correct" when they we
> > know we're talking to qemu (eg. from the CPUID) and we know it already
> > worked fine before with qemu?
> >
> Qemu has nothing to do with that. ins/outs didn't worked correctly for
> some situation. They didn't work at all if destination/source memory
> was MMIO (didn't work as in hang vcpu IIRC and this is security risk).
> Direction flag wasn't handled at all (if it was set instruction injected
> #GP into a gust). It didn't check that memory it writes to is shadowed
> in which case special action should be taken. It didn't delivered events
> during long string operations. May be more. Unfortunately adding all that
> makes emulation much slower. I already implemented some speedups, and
> more is possible, but we will not be able to get to previous string io speed
> which was our upper limit.
Thanks for the explanation. I'll repost my "DMA"-like fw-cfg patch
once I've rebased it and done some more testing. This huge regression
for a common operation (implementing -initrd) needs to be solved
without using inb/rep ins.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
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- [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Richard W.M. Jones, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Gleb Natapov, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Richard W.M. Jones, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Gleb Natapov, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?,
Richard W.M. Jones <=
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Avi Kivity, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Richard W.M. Jones, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Avi Kivity, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Richard W.M. Jones, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Avi Kivity, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Richard W.M. Jones, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Avi Kivity, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Anthony Liguori, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Avi Kivity, 2010/08/03
- Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?, Anthony Liguori, 2010/08/03