On 09/01/2015 08:45 AM, Jason J. Herne wrote: > Provide a method to throttle guest cpu execution. CPUState is augmented with > timeout controls and throttle start/stop functions. To throttle the guest cpu > the caller simply has to call the throttle set function and provide a > percentage > of throttle time. > > Signed-off-by: Jason J. Herne <jjhe...@linux.vnet.ibm.com> > Reviewed-by: Matthew Rosato <mjros...@linux.vnet.ibm.com> > --- > cpus.c | 78 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/qom/cpu.h | 43 ++++++++++++++++++++++++++++++ > 2 files changed, 121 insertions(+) >
> +/** > + * cpu_throttle_set: > + * @new_throttle_pct: Percent of sleep time to running time. I don't think you mean the ratio of sleep time to running time, as much as sleep time to overall time. That is, 10% should mean "sleep 1ms and run 9ms out of every 10ms total", and not "sleep 1ms after every 10ms run, for 90.9% duty cycle". > + * Valid range is 1 to 99. > + * > + * Throttles all vcpus by forcing them to sleep for the given percentage of > + * time. A throttle_percentage of 50 corresponds to a 50% duty cycle roughly. > + * (example: 10ms sleep for every 10ms awake). 50% can be a bit ambiguous (not obvious whether a higher percentage means more sleep or more time awake); it might be better to pick a different number, such as: A throttle_percentage of 25 corresponds to a 75% duty cycle (example: 10ms sleep for every 30ms awake). if the percentage really is [1 - duty cycle] (which I suspect), or: A throttle_percentage of 25 corresponds to a 80% duty cycle (example: 10ms sleep for every 40ms awake). (if I'm wrong, and you really meant percentage of sleep time to running time). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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