[Xen-devel] Re: Accounting in Credit Scheduler

["Mike D. Day" <ncmike@xxxxxxxxxx>]

On 09/04/07 15:40 +0100, rahul gundecha wrote:
>   thanks alot Mike for kind reply.
>   One more curiousity is how often a timer routine is called & how often
>   scheduling code?  It may be configurable interval as well, but then
>   whats default value.
>   I guess timer is called more frequently & call to scheduling routine
>   is made less frquently and is called from timer itself.
>   Can I get pointer to some reference where I will get to know how
>   exactly this mechanism works. May be digging through code will be
>   expensive option so I want to avoid it for a moment.
>   thanks,
>   -rahul

The timer is initialized in xen/common/sched_credit.c: 

static __init int csched_start_tickers(void)
{
   struct csched_pcpu *spc;
   unsigned int cpu;

   for_each_online_cpu ( cpu )
   {
       spc = CSCHED_PCPU(cpu);
       set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK));
   }

   return 0;
}


CSCHED_MSECS_PER_TICK is #defined as 10, so the accounting code runs
every 10 ms - for each physical processor.

Mike

--
Mike D. Day
IBM LTC
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