Re: Enabling PARAVIRT stuff in Fedora kernels

[Roland Dreier]

> I just tried the latest Fedora rawhide kernel
> (2.6.26-0.115.rc9.git2.fc10.x86_64) in a kvm virtual machine, and I
> noticed that it doesn't have all the paravirtual goodness available in
> 2.6.26.  The cost of setting PARAVIRT, PARAVIRT_CLOCK and
> PARAVIRT_GUEST to 'y' is suposed to be pretty minimal on bare metal,
> and it gives a nice boost running inside kvm.  Have you guys
> considered turning on these options for Fedora kernels?

And actually the options I'm really hoping for are KVM_GUEST and
KVM_CLOCK -- sorry for my confusion and sloppy grep for "VIRT".

Thanks,
  Roland

Enabling PARAVIRT stuff in Fedora kernels

[Dave Jones]

On Tue, Jul 08, 2008 at 08:25:31PM -0700, Roland Dreier wrote:
> > I just tried the latest Fedora rawhide kernel
> > (2.6.26-0.115.rc9.git2.fc10.x86_64) in a kvm virtual machine, and I
> > noticed that it doesn't have all the paravirtual goodness available in
> > 2.6.26.  The cost of setting PARAVIRT, PARAVIRT_CLOCK and
> > PARAVIRT_GUEST to 'y' is suposed to be pretty minimal on bare metal,
> > and it gives a nice boost running inside kvm.  Have you guys
> > considered turning on these options for Fedora kernels?
>
> And actually the options I'm really hoping for are KVM_GUEST and
> KVM_CLOCK -- sorry for my confusion and sloppy grep for "VIRT".

Umm, they're also all enabled.

Dave

Enabling PARAVIRT stuff in Fedora kernels

[Roland Dreier]

> > And actually the options I'm really hoping for are KVM_GUEST and
> > KVM_CLOCK -- sorry for my confusion and sloppy grep for "VIRT".
>
> Umm, they're also all enabled.

$ grep KVM /boot/config-2.6.26-0.115.rc9.git2.fc10.x86_64 
CONFIG_HAVE_KVM=y
CONFIG_KVM=m
CONFIG_KVM_INTEL=m
CONFIG_KVM_AMD=m
CONFIG_KVM_TRACE=y
$ grep PARAVIRT /boot/config-2.6.26-0.115.rc9.git2.fc10.x86_64 
# CONFIG_PARAVIRT_GUEST is not set

Is there a newer kernel somewhere?  That one is the latest I find in
http://mirrors.cat.pdx.edu/fedora/linux/development/x86_64/os/Packages
and the rpm says "Build Date: Mon 07 Jul 2008 07:36:11 PM PDT" so it's
pretty recent.

Thanks,
  Roland

Enabling PARAVIRT stuff in Fedora kernels

[Dave Jones]

On Tue, Jul 08, 2008 at 09:28:43PM -0700, Roland Dreier wrote:
> > > And actually the options I'm really hoping for are KVM_GUEST and
> > > KVM_CLOCK -- sorry for my confusion and sloppy grep for "VIRT".
> >
> > Umm, they're also all enabled.
>
> $ grep KVM /boot/config-2.6.26-0.115.rc9.git2.fc10.x86_64 
> CONFIG_HAVE_KVM=y
> CONFIG_KVM=m
> CONFIG_KVM_INTEL=m
> CONFIG_KVM_AMD=m
> CONFIG_KVM_TRACE=y
> $ grep PARAVIRT /boot/config-2.6.26-0.115.rc9.git2.fc10.x86_64 
> # CONFIG_PARAVIRT_GUEST is not set

Ah, yeah. See my note about x86-64 in the other mail.
I'll flip it on tomorrow, and we'll see if it builds now..

Dave

Enabling PARAVIRT stuff in Fedora kernels

[Roland Dreier]

> Ah, yeah. See my note about x86-64 in the other mail.
> I'll flip it on tomorrow, and we'll see if it builds now..

As a test report: with kernel 2.6.26-0.124.rc9.git5.fc10.x86_64, I'm
seeing paravirt and kvm paravirt clock working as a guest inside kvm 70.

Thanks,
  Roland