On 03/04/2011 02:09 PM, Glauber Costa wrote:
On Fri, 2011-03-04 at 19:27 +0100, Nikola Ciprich wrote:
Hello Zachary,
You don't see any messages about TSC being unstable or switching
clocksource after loading the KVM module? And you are not suspending
the host or anything?
no messages, no suspending, nothing.
Can you try using "processor.max_cstate=1" on the host as a kernel
parameter and see if it makes a difference?
I tried it, no change..
n.
Zach,
I don't understand 100 % the logic behind all your tsc changes.
But kvm-clock-wise, most of the problems we had in the past were related
to the difference in resolution between the tsc and the host clocksource
(hpet, acpi_pm, etc), which in his case, it is a non-issue.
It does seem to me like some compensation logic kicked in, dismantling
an otherwise good tsc. He does have nonstop_tsc, which means it can't
get any better.
One thing I noticed when reading the culprit patch in bisect, is that in
vcpu_load(), there were previously a call to
kvm_request_guest_time_update(vcpu)
that was removed without a counterpart addition. Any idea about why it
was done?
That's probably the source of the bug... I've been looking for that
exact line, though, and I can't find it missing.
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