Re: [PATCH V2 0/2] percpu_ref & block: reduce memory footprint of percpu_ref in fast path

[Jens Axboe]

On 9/2/20 6:26 AM, Ming Lei wrote:
> Hi,
> 
> The 1st patch removes memory footprint of percpu_ref in fast path
> from 7 words to 2 words, since it is often used in fast path and
> embedded in user struct.
> 
> The 2nd patch moves .q_usage_counter to 1st cacheline of
> 'request_queue'.
> 
> Simple test on null_blk shows ~2% IOPS boost on one 16cores(two threads
> per core) machine, dual socket/numa.
> 
> V2:
> 	- pass 'gfp' to kzalloc() for fixing block/027 failure reported by
> 	kernel test robot
> 	- protect percpu_ref_is_zero() with destroying percpu-refcount by
> 	spin lock  
> 
> Ming Lei (2):
>   percpu_ref: reduce memory footprint of percpu_ref in fast path
>   block: move 'q_usage_counter' into front of 'request_queue'

Applied, thanks.

-- 
Jens Axboe