Re: [Xen-devel] [PATCH v2 5/6] virt, sched: add cpu pinning to smp_call_sync_on_phys_cpu()

[Juergen Gross <jgross@xxxxxxxx>]

On 21/03/16 14:42, Jan Beulich wrote:
>>>> On 21.03.16 at 13:24, <JGross@xxxxxxxx> wrote:
>> @@ -758,9 +759,14 @@ struct smp_sync_call_struct {
>>  static void smp_call_sync_callback(struct work_struct *work)
>>  {
>>      struct smp_sync_call_struct *sscs;
>> +    unsigned int cpu = smp_processor_id();
> 
> So this obtains the vCPU number, yet ...
> 
>>      sscs = container_of(work, struct smp_sync_call_struct, work);
>> +    preempt_disable();
>> +    hypervisor_pin_vcpu(cpu);
> 
> ... here you're supposed to pass a pCPU number.
> 
> Also don't you need to call smp_processor_id() after preempt_disable()?

No, I'm running on the workqueue bound to the specific (v)cpu and I'm
expecting this vcpu to be pinned to the same numbered pcpu.

preempt_disable() is just called to avoid scheduling of another thread
while the override pinning is active.


Juergen

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