Re: [Xen-devel] How to migrate vCPUs based on Credit Scheduler

[Lars Kurth <lars.kurth.xen@xxxxxxxxx>]

Adding George, Dario & Anshul
Lars

> On 3 Apr 2017, at 17:21, 甘清甜 <qingtiangan@xxxxxxxxx> wrote:
> 
> Hi,
> 
>  I'm now designing new vCPU scheduler in Xen, and trying to implement 
> the scheduler based on the Credit scheduler in Xen-4.5.1. But I encountered
>  come problems when debuging the code.
> 
> Most of the code modification is done in function csched_schedule() in 
> file: xen/common/csched_schedule.c . And the core code is as followed:
> 
> if( vcpu_runnable(current) )
> {
>         if( match the migration contition )
>         {
>             cpu_affinity = pick_pcpu_runq();  // this function is defined by 
> myself
>             
>             pcpulock = pcpu_schedule_lock_irqsave(cpu_affinity, 
>                    &pcpulock_flag);
> 
>             TRACE_3D(TRC_CSCHED_STOLEN_VCPU, cpu_affinity  , domain_id,
>                    vcpu_id);
>             SCHED_VCPU_STAT_CRANK(scurr, migrate_q);
>             SCHED_STAT_CRANK(migrate_queued);
>             WARN_ON(scurr->vcpu->is_urgent);
>           scurr->vcpu->processor = cpu_affinity;      
> 
>              __runq_insert(cpu_affinity, scurr);
>             pcpu_schedule_unlock_irqrestore(pcpulock, pcpulock_flag, 
> cpu_affinity  );
>         }
>         else 
>             __runq_insert(cpu, scurr);
> }
> else 
>         BUG_ON( is_idle_vcpu(current) || list_empty(runq) );
> 
> 
> I try to run the modified Xen. But according to the log I found that, 
> although I insert the vCPU into the runqueue  of another pCPU, the 
> vCPU still appears at the old pCPU in the following scheduling period. 
> Now I have a few questions:
> 
> 1. Does the Xen scheduler framework support changing the pCPU of a 
> vCPU after using out the scheduling time slice, but not just to steal one 
> vCPU from runqueue of other pCPU in load_balance period?
> 
> 2. If yes, what status of the vCPU should be changed before inserting 
> the vCPU into the destination pCPU?
> 
> Thank you very much!
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> https://lists.xen.org/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel