[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH, RFC] x86/HVM: batch vCPU wakeups

At 23:37 +0100 on 09 Sep (1410302243), Andrew Cooper wrote:
> >> +void cpu_raise_softirq_batch_finish(void)
> >> +{
> >> +    unsigned int cpu, this_cpu = smp_processor_id();
> >> +    cpumask_t *mask = &per_cpu(batch_mask, this_cpu);
> > Again, this_cpu()?
> ...But disagree here.  Multiple uses of this_cpu($FOO) cannot be
> coalesced due to RELOC_HIDE() deliberately preventing optimisation.  For
> multiple uses, pulling it out by pointer to start with results in rather
> more efficient code.

I wasn't questioning the pointer, but to the use of per_cpu(...,
this_cpu) instead of this_cpu(...).  Both of those involve a

Anyway, it's pretty clear from your and Jan's replies that multiple
this_cpu() invocations are slower -- thanks for the clarification!


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.