Re: [Xen-devel] [PATCH v3 for Xen 4.6 3/4] libxl: enable per-VCPU parameter settings for RTDS scheduler

[Chong Li <lichong659@xxxxxxxxx>]

On Tue, Jun 30, 2015 at 10:57 AM, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> On Tue, 2015-06-30 at 10:42 -0500, Chong Li wrote:
>> >> @@ -1554,10 +1564,17 @@ int libxl_sched_credit_params_set(libxl_ctx *ctx, 
>> >> uint32_t poolid,
>> >>  #define LIBXL_DOMAIN_SCHED_PARAM_EXTRATIME_DEFAULT -1
>> >>  #define LIBXL_DOMAIN_SCHED_PARAM_BUDGET_DEFAULT    -1
>> >>
>> >> +/* Per-VCPU parameters*/
>> >> +#define LIBXL_DOMAIN_SCHED_PARAM_VCPU_INDEX_DEFAULT -1
>> >
>> > What is the effect of passing vcpuid == -1 to this interface?
>>
>> I think the right way should be:
>>
>> #define LIBXL_SCHED_PARAM_VCPU_INDEX_DEFAULT -1
>>
>> which is the default value for the vcpuid in libxl_sched_params. Even
>> though libxl_sched_params is used for per-vcpu settings, all the other
>> fields (except vcpuid) would still use
>> LIBXL_DOMAIN_SCHED_PARAM_*_DEFAULT values, just for convenience.
>
> My question is what does the concept of vcpu==-1 mean in this interface?

We need a default value for vcpuid when initiating libxl_sched_params,
just like other fields (e.g., budget, weight ...) in the struct. But
the default value could be others, maybe "0". I'm not sure.
>
> Ian.
>



-- 
Chong Li
Department of Computer Science and Engineering
Washington University in St.louis

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