Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?

[Avi Kivity <avi@redhat.com>]

  On 08/03/2010 08:42 PM, Anthony Liguori wrote:
> However, I don't think we can objectively differentiate between a 
> "major" and "minor" user.  Generally speaking, I would rather that we 
> not take the position of "you are a minor user therefore we're not 
> going to accommodate you".

Again it's a matter of practicalities.  With have written virtio drivers 
for Windows and Linux, but not for FreeDOS or NetWare.  To speed up 
Windows XP we have (in qemu-kvm) kvm-tpr-opt.c that is a gross breach of 
decency, would we go to the same lengths to speed up Haiku?  I suggest 
that we would not.

libvirt and Windows XP did not win "major user" status by making large 
anonymous donations to qemu developers.  They did so by having lots of 
users.  Those users are our end users, and we should be focusing our 
efforts in a way that maximizes the gain for as large a number of those 
end users as we can.

Not breaking libvirt will be unknowingly appreciated by a large number 
of users, every day.  Not slowing down libguestfs, by a much smaller 
number for a much shorter time.  If it were just a matter of changing 
the help text I wouldn't mind at all, but introducing an undocumented 
migration-unsafe broken-dma interface isn't something I'm happy to do.

btw, gaining back some of the speed that we lost _is_ something I want 
to do, since it doesn't break or add any interfaces, and would be a gain 
not just for libguestfs, but also for Windows installs (which use string 
pio extensively).  Richard, can you test kvm.git master?  it already 
contains one fix and we plan to add more.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.