On Mon, Apr 17, 2017 at 12:03:53AM +0800, Ming Lei wrote: > On Sat, Apr 15, 2017 at 08:38:21PM +0800, Ming Lei wrote: > > The 1st patch enhances BLK_MQ_F_NO_SCHED so that we can't change/ > > show available io schedulers on devices which don't support io > > scheduler. > > > > The 2nd patch passes BLK_MQ_F_NO_SCHED for avoiding one regression > > on mtip32xx, which is introduced by blk-mq io scheduler. > > > > The last two patches introduce BLK_MQ_F_SCHED_USE_HW_TAG so that > > we can allow to use hardware tag for scheduler, then mq-deadline > > can work well on mtip32xx. Even though other devices with enough > > hardware tag space can benefit from this feature too. > > > > The 1st two patches aims on v4.11, and the last two are for > > v4.12. > > Please ignore this patchset, and I will post another serial for > mtip32xx fix. > > thanks, > Ming Regardless of the mtip32xx fix, I actually wanted to skip the scheduler tags when possible just for performance reasons. I don't think that should be a device-specific setting. We can let the I/O scheduler decide how many tags it wants, and if the device has at least that many tags, just use the hardware tags directly. I'll probably look at doing that for 4.13, we'll see if it actually makes a performance difference.
