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Re: [PATCH 0/4] block: account io: kill atomic operations

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On 07/15/2015 09:16 PM, Ming Lei wrote:
> Hi,
>
> This patches kills two kinds of atomic operations in block
> accounting I/O.
>
> The 1st two patches convert atomic refcount of partition
> into percpu refcount.
>
> The 2nd two patches converts partition->in_flight[] into percpu
> variable.
>
> With this change, ~15% throughput improvement can be observed
> when running fio(randread) over null blk in a dual-socket
> environment.

I've played with this before, but always ran into the hurdle of making 
part_in_flight() too expensive ended up hurting results in the end. 
Making the inc/dec parts of accounting percpu is a no-brainer, 
unfortunately the summing then becomes pretty expensive. I'll run this 
through some testing and see what kind of results I get.

-- 
Jens Axboe

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[PATCH 0/4] block: account io: kill atomic operations Ming Lei <tom.leiming@gmail.com> - 2015-07-16 05:20 +0200
  [PATCH 3/4] block: partition: introduce 'cpu' para to part_inc|dec_in_flight Ming Lei <tom.leiming@gmail.com> - 2015-07-16 05:30 +0200
  [PATCH 1/4] block: partition: introduce hd_free_part() Ming Lei <tom.leiming@gmail.com> - 2015-07-16 05:30 +0200
  [PATCH 2/4] block: partition: convert percpu ref Ming Lei <tom.leiming@gmail.com> - 2015-07-16 05:30 +0200
    Re: [PATCH 2/4] block: partition: convert percpu ref Tejun Heo <tj@kernel.org> - 2015-07-16 16:40 +0200
  [PATCH 4/4] block: account io: convert part->in_fligh[] into percpu variable Ming Lei <tom.leiming@gmail.com> - 2015-07-16 05:30 +0200
    Re: [PATCH 4/4] block: account io: convert part->in_fligh[] into  percpu variable Tejun Heo <tj@kernel.org> - 2015-07-16 16:50 +0200
  Re: [PATCH 0/4] block: account io: kill atomic operations Jens Axboe <axboe@kernel.dk> - 2015-07-16 16:50 +0200
    Re: [PATCH 0/4] block: account io: kill atomic operations Tejun Heo <tj@kernel.org> - 2015-07-16 17:00 +0200
      Re: [PATCH 0/4] block: account io: kill atomic operations Jens Axboe <axboe@kernel.dk> - 2015-07-16 17:10 +0200
    Re: [PATCH 0/4] block: account io: kill atomic operations Jens Axboe <axboe@kernel.dk> - 2015-07-16 17:10 +0200
    Re: [PATCH 0/4] block: account io: kill atomic operations Ming Lei <tom.leiming@gmail.com> - 2015-07-16 17:10 +0200

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