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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