Re: [Qemu-devel] Boot Problems Windows XP guest

[Benoît Canet]

Le Wednesday 28 Aug 2013 à 15:14:41 (+0200), Paolo Bonzini a écrit :
> Il 28/08/2013 11:07, Erik Rull ha scritto:
> >>> It could be a real difference, actually.  An unexpectedly fast disk
> >>> might screw a sloppy driver.  IIRC you're not the first person reporting
> >>> it.  Stefan, do you think using block throttling could fix it (with some
> >>> trial and error)?
> >>
> >> That might work.  You could start with something like -drive ...,iops=20
> >> and then disable the limit from the QEMU monitor once the guest OS is
> >> booting (block_set_io_throttle virtio0 0 0 0 0 0 0).
> >>
> >> It would be easier to try -drive ...,cache=writethrough and -win2k-hack
> >> first as Anthony suggests.
> >>
> >> Stefan
> > 
> > Thanks.
> > I tried that, but when should I reset the throttle?
> 
> Never.  The bug will be there through the whole execution of the guest.
> 
> > When I reset it some seconds
> > after the BIOS screen disappeared same result as without throttling. When I 
> > keep
> > it, Windows still reboots, the cycle just takes longer (half an hour), but 
> > the
> > progress seems to be the same as without throttle.
> 
> On second thought that is expected.  Until throttling kicks in, I/O will
> complete just as fast as without throttling.  Maybe limiting the number
> of bytes per second instead of I/O ops would be better.  Can you try
> -drive ...,bps=1048576 (possibly higher or lower numbers too)?
> 
> And maybe Benoit's new algorithm could help too.  Benoit, do you have a
> tree for Erik to try?

Hi Eric,

You can find my latest throttling work on the leaky_continuous_final2 branch
of the following git tree.

git clone address@hidden:benoit-canet-qemu/benoit-canet-qemu.git
git checkout leaky_continuous_final2

Hope this help

Best regards

Benoît