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[Xen-devel] Re: Accounting in Credit Scheduler

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

"Mike D. Day" <ncmike@xxxxxxxxxx> wrote:
On 09/04/07 12:03 +0100, rahul gundecha wrote:
>
> Hi..
> I was going through wiki page of Credit Scheduler which says -
> " The scheduling decision is the common path of the scheduler and is
> therefore designed to be light weight and efficient. No accounting
> takes place in this code path. "
> So where does the accounting process takes place. exctaly by which
> way accounting for CPU, different IO device usage is done. With the
> complex architecture of Xen, how does this accounting process is
> carried out?

The credit scheduler sets up a timer when it is initialized. It does
process accounting during the timer service routine.

The decision to schedule the next vcpu is done on a different code
path, and is optimized to be as fast as possible.

Mike

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Mike D. Day
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