Re: [Xen-devel] [PATCH v3 3/4] libxl: add rtds scheduler

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2014-09-15 at 21:11 -0400, Meng Xu wrote:

>         > +    if (scinfo->period !=
>         LIBXL_DOMAIN_SCHED_PARAM_PERIOD_DEFAULT) {
>         > +        if (scinfo->period < 1) {
>         > +            LOG(ERROR, "VCPU period is not set or out of
>         range, "
>         > +                       "valid values are larger than 1");
>         
>         There's no upper limit? Likewise for the budget further down?
> 
> 
> âYes. In the previous version, I used the UINT_MAX as the upper bound.
> Because period is int, so it will never reach the UINT_MAX. Even if I
> change the UINT_MAX to INT_MAX as the upper bound, period may still
> not able to reach it. So George suggests to remove the upper bound
> check if it uses the range of type of period. 
> 
> 
> Since period is int, the largest period we support should be 2^31-1us
> = 0.5965 hours. That's why we don't have the upper bound check. Of
> course, I can add the upper bound as INT_MAX (2^31-1) and reports
> error when users try to assign a large value to period and budget.
> 
> 
> What do you think?

If the upper limit is the same as the maximum value of the field then
there is no need for a check.

Is a 0.5hr maximum period considered to be larger than any practically
useful value?

Ian.


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