Many mfgpt timer interrupts with tickless kernel

[William Cohen]

Jordan Crouse wrote:
> On 22/03/07 18:26 +0100, Jens Axboe wrote:
>> The tickless kernel just _enables_ low number of interrupts per second,
>> it'll still wakeup everytime something is scheduled to run. So you
>> probably want to look into _why_ th timer interrupts happen so often -
>> who is the user of them?
>>
>> I see ~70 interrupts/sec here with an idle machine in X, FWIW.
> 
> I've seen it as low as 10 on a very very quiet machine.  Enable the timer
> statistics and run a sample - I'll bet you see some offenders like the
> console cursor, the libertas, and other such greedy consumers of our time.
> 
> Jordan
> 

Jordan,

Thanks for the pointer.  Looking through /proc/timer_list give a list of 
possible offenders.  I also tried running with and without systemtap script 
running. Without the systemtap script the mfgpt-timers irq dropped to about 
40/sec. So it appears that systemtap probe is causing the timer to fire more often.

-Will