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xen-devel
[Xen-devel] Xen cpufreq support status: how to notify hypervisor of freq
Hi,
I previously posted a patch to make the dom0 cpufreq drivers properly use
DOM0_MSR (instead of wrmsr) to adjust the processor frequency and voltage.
This does indeed adjust the frequency, but Xen seems to have major latency
problems whenever the frequency change takes affect, causing various problems
like losing mouse events, uncontrolled keyboard repeats, and choppy audio and
video playback for a few seconds after the shift.
This appears to happen because virtual timer interrupts do not get delivered
on a regular basis for a few seconds following the frequency change.
Assuming we want to keep the cpufreq driver itself in dom0, what's the proper
way to notify the hypervisor that the CPU frequency has just changed, so it
can adjust its timers like the cpufreq driver on the native kernel does?
I'd really like to have cpufreq working properly under Xen (for both
workstations and to a lesser extent servers), so what would be the best way
to get this running?
- Matt Yourst
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Matt T. Yourst yourst@xxxxxxxxxxxxxxxxx
Binghamton University, Department of Computer Science
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