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

From: Christoph Lameter
Date: Wed Aug 07 2013 - 15:40:23 EST

On Wed, 7 Aug 2013, Kent Overstreet wrote:

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

this_cpu can be retrieved with smp_processor_id().

> 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.

Yes it is. It uses a sepecial register that contains the offset of this
cpus per cpu area instead of going through the table of all processor
offsets. Its less code.

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