On 04/28/2017 09:15 AM, Ming Lei wrote: > Hi, > > This patchset introduces flag of BLK_MQ_F_SCHED_USE_HW_TAG and > allows to use hardware tag directly for IO scheduling if the queue's > depth is big enough. In this way, we can avoid to allocate extra tags > and request pool for IO schedule, and the schedule tag allocation/release > can be saved in I/O submit path.
Ming, I like this approach, it's pretty clean. It'd be nice to have a bit of performance data to back up that it's useful to add this code, though. Have you run anything on eg kyber on nvme that shows a reduction in overhead when getting rid of separate scheduler tags? -- Jens Axboe
