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

On 21/03/16 14:42, Jan Beulich wrote:

quoted

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On 21.03.16 at 13:24, [off-list ref] 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 ...

quoted

 	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