Re: [PATCH RFC v2 1/4] xen: add real time scheduler rt

[Dario Faggioli <raistlin.df@gmail.com>]

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On mar, 2014-07-29 at 07:52 +0100, Jan Beulich wrote:
> >>> On 29.07.14 at 03:52, <mengxu@cis.upenn.edu> wrote:

> > --- a/xen/include/public/domctl.h
> > +++ b/xen/include/public/domctl.h
> > @@ -339,6 +339,18 @@ struct xen_domctl_max_vcpus {
> >  typedef struct xen_domctl_max_vcpus xen_domctl_max_vcpus_t;
> >  DEFINE_XEN_GUEST_HANDLE(xen_domctl_max_vcpus_t);
> >  
> > +/*
> > + * This structure is used to pass to rt scheduler from a 
> > + * privileged domain to Xen
> > + */
> > +struct xen_domctl_sched_rt_params {
> > +    /* get vcpus' info */
> > +    int64_t period; /* s_time_t type */
> > +    int64_t budget;
> > +    int     index;
> 
> Are all these really meaningfully signed quantities?
> 
The scheduler internal variable where the actual budget is kept updated
needs, IMO, to be signed (s_time_t is the best choice). However, as far
as the interface is concerned, I think Jan is right, being able to
specify a negative budget and period is not that useful! :-P

I think you can go for unsigned quantities here, while s_time_t is
certainly ok inside the scheduler.

Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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