Re: [PATCH] Add condition to stop issuing io in do_io().

[Jens Axboe <axboe@kernel.dk>]

On 09/16/2013 10:22 AM, Juan Casse wrote:
> Problem:
> When specifying iodepth > 1 while doing random async io
> without a random map (and using the default random generator), the
> main while loop in do_io() will issue extra io in the amount of io
> allowed to accumulate in the queue. For example, a job with size=24k
> and bs=8k will perform 4 io instead of the expected 3.
> 
> Reason:
> The above behavior occurs because the while loop in do_io()
> will continue until the amount of "completed io" >= size, but io
> in the queue are not accounted for because they have not been
> completed by io_u_queued_complete().
> 
> Exceptions:
> The above behavior does not manifest itself when:
> 	using random_generator=lfsr bacause lfsr knows when to stop
> 	generating, and get_io_u() inside the while loop returns NULL,
> 	breaking out of the loop.
> 	using random map because random map ensures that all blocks
> 	are hit, and after they are all hit, no more are generated.
> 
> Proposed Solution:
> Stop while loop based on bytes issued instead of bytes completed.

Looks good, applied.

-- 
Jens Axboe