On 10/16/18 9:33 AM, Vincent Fu wrote: > On 10/16/2018 11:29 AM, Jens Axboe wrote: >> On 10/16/18 9:26 AM, vincentfu@xxxxxxxxx wrote: >>> From: Vincent Fu <vincent.fu@xxxxxxx> >>> >>> serialize_overlap combined with io_submit_mode=offload requires >>> threads. Print a warning and force the use of threads if the user >>> did not specify threads. >> Why does it require threads? Is it because of the use of a pthread >> mutex? If so, that should just be a fio mutex instead, and you would >> not have this restrictions (on most platforms, at least). >> > It requires threads because io_u's are not allocated from the shared > memory area. Jobs need to access each other's io_u's to check for overlap. Gotcha. Might be better to change that rather than impose limitations on needing threads for this specific configuration. Probably make it dependent on offload and serialize_overlap for now, it'd be less risky. The risk here being that higher queue depth jobs running out of memory in the smalloc pool. -- Jens Axboe
