On Friday, November 03, 2017 03:20:10 PM Adrian Hunter wrote: > Hi > > Here is V13 of the hardware command queue patches without the software > command queue patches, now using blk-mq and now with blk-mq support for > non-CQE I/O. > > HW CMDQ offers 25% - 50% better random multi-threaded I/O. I see a slight > 2% drop in sequential read speed but no change to sequential write. > > Non-CQE blk-mq showed a 3% decrease in sequential read performance. This > seemed to be coming from the inferior latency of running work items compared > with a dedicated thread. Hacking blk-mq workqueue to be unbound reduced the > performance degradation from 3% to 1%. > > While we should look at changing blk-mq to give better workqueue performance, > a bigger gain is likely to be made by adding a new host API to enable the > next already-prepared request to be issued directly from within ->done() > callback of the current request. Tested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> [ for non-CQE changes ] Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics
