Re: [Xen-devel] [PATCH v2 for Xen 4.6 1/4] xen: enabling XL to set per-VCPU parameters of a domain for RTDS scheduler

[Chong Li <lichong659@xxxxxxxxx>]

On Tue, May 26, 2015 at 12:18 PM, Chong Li <lichong659@xxxxxxxxx> wrote:
> On Tue, May 26, 2015 at 4:08 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>> On 26.05.15 at 02:05, <lichong659@xxxxxxxxx> wrote:
>>> Add two hypercalls(XEN_DOMCTL_SCHEDOP_getvcpuinfo/putvcpuinfo) to get/set a
>>> domain's
>>> per-VCPU parameters. Hypercalls are handled by newly added hook
>>> (.adjust_vcpu) in the
>>> scheduler interface.
>>>
>>> Add a new data structure (struct xen_domctl_scheduler_vcpu_op) for
>>> transferring data
>>> between tool and hypervisor.
>>>
>>> Signed-off-by: Chong Li <chong.li@xxxxxxxxx>
>>> Signed-off-by: Meng Xu <mengxu@xxxxxxxxxxxxx>
>>> Signed-off-by: Sisu Xi <xisisu@xxxxxxxxx>
>>> ---
>>
>> Missing brief description of changes in v2 here.
>
> Based on Dario's suggestion in PATCH v1, we think it would be better
> to make the per-vcpu get/set functionalities more general, rather than
> just serving for rtds scheduler. So, the changes in v2 are:
>
> 1) Add a new hypercall, XEN_DOMCTL_scheduler_vcpu_op. Any scheduler
> can use it for per-vcpu get/set. There is a new data structure (struct
> xen_domctl_scheduler_vcpu_op), which helps transferring data (per-vcpu
> params) between tool and hypervisor when the hypercall is invoked.
>
> 2) The new hypercall is handled by function sched_adjust_vcpu (in
> schedule.c), which would call a newly added hook (named as
> .adjust_vcpu, added to the scheduler interface (struct scheduler)).
>
> 3) In RTDS scheduler, .adjust_vcpu hooks a function defined in
> sched_rt.c, named as rt_vcpu_cntl. This function gets/sets the
> per-vcpu params.
>
>

>>
>>> --- a/xen/common/schedule.c
>>> +++ b/xen/common/schedule.c
>>> @@ -1104,6 +1104,30 @@ long sched_adjust(struct domain *d, struct 
>>> xen_domctl_scheduler_op *op)
>>>      return ret;
>>>  }
>>>
>>> +/* Adjust scheduling parameter for the vcpus of a given domain. */
>>> +long sched_adjust_vcpu(
>>> +    struct domain *d,
>>> +    struct xen_domctl_scheduler_vcpu_op *op)
>>> +{
>>> +    long ret;
>>
>> I see no reason for this and the function return type to be "long".
>
> The reason is stated in the begining.

Sorry for missing some details in the last reply.

sched_adjust_vcpu is added here because I need a seperate function to
handle XEN_DOMCTL_scheduler_vcpu_op, which is a new hypercall
dedicated for per-vcpu get/set. This function is actually based on
sched_adjust (which is dedicated for per-dom get/set in rtds), so the
return type is also the same.

>
>>
>> Jan
>>
>
> Best,
> Chong
>
> --
> Chong Li
> Department of Computer Science and Engineering
> Washington University in St.louis



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

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