Re: [Xen-devel] RE: rdtsc strangeness on upstream kernel

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 07/19/2010 04:55 PM, Dan Magenheimer wrote:
>> With vcpus=2, timer0 goes up to about 2000 irq/sec on CPU0
>> and timer1 on CPU1 is the same while rdtsc/sec is about 20000.
>>     
> No, wait, correct that...timer0 and timer1 are 1000 irq/sec.
> (I was using "watch -d" which defaults to updating every
> two seconds, not every second.)
>
>   
>> Is it possible that the timer interrupt is using rdtsc
>> five times each interrupt?
>>     
> TEN times each interrupt.
>   

Do you have any other debugging/tracing enabled?  CONFIG_XEN_DEBUG_FS
for example?

10 sounds a little high, but not necessarily completely unreasonable,
especially if there's tracing/debugging on.

    J

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