Re: [PATCH]block: make auto block plug flush threshold per-disk based

[Jeff Moyer]

Jens Axboe <axboe@xxxxxxxxx> writes:

> On 2012-04-06 11:27, Shaohua Li wrote:
>> We do auto block plug flush to reduce latency, the threshold is 16
>> requests. This works well if the task is accessing one or two drives.
>> The problem is if the task is accessing a raid 0 device and the raid
>> disk number is big, say 8 or 16, 16/8 = 2 or 16/16=1, we will have
>> heavy lock contention.
>> 
>> This patch makes the threshold per-disk based. The latency should be
>> still ok accessing one or two drives. The setup with application
>> accessing a lot of drives in the meantime uaually is big machine,
>> avoiding lock contention is more important, because any contention
>> will actually increase latency.
>
> Thanks, applied. It should have been per-queue all along, so this
> makes a lot of sense.

Yeah, I had noticed this before when looking over the code.  Makes
sense.

Acked-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
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