Re: [Xen-devel] [PATCH v2] xen/credit scheduler; Use delay to control scheduling frequency

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Mon, Dec 19, 2011 at 8:24 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>> +         && vcpu_runnable(current)
>> +         && !is_idle_vcpu(current)
>> +         && runtime < MICROSECS(sched_ratelimit_us) )
>> +    {
>> +        snext = scurr;
>> +        snext->start_time += now;
>> +        perfc_incr(delay_ms);
>> +        tslice = MICROSECS(sched_ratelimit_us);
>
> So if there happens to be a VM with
>
> MILLISECS(prv->tslice_ms) < MICROSECS(sched_ratelimit_us)
>
> it'd get *more* time than allowed/intended through this mechanism.

Yeah, if you set your default timeslice to 1ms, and then set your
minimum scheduling rate to 5ms, you're going to get weird results. :-)

The way it stands now, the ratelimit value will override the timeslice
value.  It had to be one way or the other; do you think the timeslice
value should be the priority?

 -George

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel