Re: [PATCH V7 1/2] percpu_ref: reduce memory footprint of percpu_ref in fast path

Tejun Heo
2020-10-01T15:50:24Z

On Thu, Oct 01, 2020 at 11:48:41PM +0800, Ming Lei wrote:
> 'struct percpu_ref' is often embedded into one user structure, and the
> instance is usually referenced in fast path, however actually only
> 'percpu_count_ptr' is needed in fast path.
>
> So move other fields into one new structure of 'percpu_ref_data', and
> allocate it dynamically via kzalloc(), then memory footprint of
> 'percpu_ref' in fast path is reduced a lot and becomes suitable to put
> into hot cacheline of user structure.
>
> Tested-by: Veronika Kabatova <vkabatov@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Sagi Grimberg <sagi@grimberg.me>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

--
tejun