On 08/27/2018 06:41 PM, Sitsofe Wheeler wrote: > On Mon, 27 Aug 2018 at 21:41, Vincent Fu <vincentfu@xxxxxxxxx> wrote: >> From: Vincent Fu <Vincent.Fu@xxxxxxx> >> >> The Linux sg driver accepts only 16 SCSI commands in flight >> at a time per file descriptor. fio does not exit gracefully >> when it attempts to queue up 17 or more trim commands via >> the sg ioengine. This patch improves error handling in the > Does this mean the engine should refuse iodepths greater than 16 in > general or are there multiple descriptors? > The engine should not refuse iodepths greater than 16 in general. The purpose of the recent sg changes was to support high QD trim workloads by sending multiple ranges in a single SCSI command. --rw=randtrim --iodepth=256 --iodepth_batch=16 will work whereas --rw=randtrim --iodepth=257 --iodepth_batch=16 will fail.
