Sven-Thorsten Dietrich wrote:
> On Mon, 2007-10-22 at 09:01 +0200, Back, Michael (ext) wrote:
>> Hallo,
>> I tried to run Windows XP with KVM on Linux 2.6.31.1 on a
>
> You mean .21.1 ?
Classic typo I interestingly also did several times the last week. :)
>
>> AMD Opteron and on a Intel Xeon, on both it works fine!
>
>> After this test I patch the kernel with the current prempt-patch and on
>> both it doesn't works!
>
> Did you try against 2.6.23-rt1.
kvm in -rt1 is not usable. It's too old, lacking PREEMPT_NOTIFIER
support, thus quickly triggering lockdep.
>
> If you must stay on .21, you might have some other issues with the AMD
> and NUMA.
>
> At the very least, you will need to apply the attached patch from git
> somehow, although this patch is against a new scheduler post 2.6.22, so
> good luck :)
<--snip-->
Those patches are already mainline... :->
What you rather need are latest kvm patches, or - if building the kvm
distribution out of tree - a patch to enabled CONFIG_PREEMPT_NOTIFIERS
unconditionally:
--- linux-2.6.23.1-rt/kernel/Kconfig.preempt.orig
+++ linux-2.6.23.1-rt/kernel/Kconfig.preempt
@@ -136,6 +136,7 @@
config PREEMPT_NOTIFIERS
bool
+ default y
config PREEMPT_BKL
bool
Still, I'm seeing oopses here (more precisely, lock validator
complaints), but I need to re-test, better using kvm from git instead of
kvm-48.
Beyond this, I'm struggling to understand 300-400 us vm-exit latencies
(over Intel VMX), which appear to be independent of the underlying
system. See kvm-devel. Such latencies would limit the RT usability of
kvm - unless you spent dedicated CPUs.
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
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