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

Juergen Gross
Mon, 21 Mar 2016 14:21:04 -0000

On 21/03/16 14:42, Jan Beulich wrote:
>>>> On 21.03.16 at 13:24, <JGross at suse.com> 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