Re: [PATCH 04/10] idr: Percpu ida

From: Kent Overstreet
Date: Wed Aug 07 2013 - 14:39:30 EST


On Wed, Aug 07, 2013 at 05:56:34PM +0000, Christoph Lameter wrote:
> On Wed, 7 Aug 2013, Kent Overstreet wrote:
>
> > +{
> > + DEFINE_WAIT(wait);
> > + struct percpu_ida_cpu *tags;
> > + unsigned long flags;
> > + unsigned this_cpu;
> > + int tag;
> > +
> > + local_irq_save(flags);
>
> > + this_cpu = smp_processor_id();
> > + tags = per_cpu_ptr(pool->tag_cpu, this_cpu);
>
> tags = this_cpu_ptr(pool->tag_cpu);

I was breaking it apart because I was using this_cpu elsewhere too - for
the bitmap of which cpus have non empty freelists.

Or is this_cpu_ptr() doing something smarter than per_cpu_ptr(ptr,
smp_processer_id())? There's so many variants I'm not 100% sure they're
the same.
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