On 3/7/22 11:53 AM, Mike Snitzer wrote: > From: Ming Lei <ming.lei@xxxxxxxxxx> > > Support bio(REQ_POLLED) polling in the following approach: > > 1) only support io polling on normal READ/WRITE, and other abnormal IOs > still fallback to IRQ mode, so the target io is exactly inside the dm > io. > > 2) hold one refcnt on io->io_count after submitting this dm bio with > REQ_POLLED > > 3) support dm native bio splitting, any dm io instance associated with > current bio will be added into one list which head is bio->bi_private > which will be recovered before ending this bio > > 4) implement .poll_bio() callback, call bio_poll() on the single target > bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call > dm_io_dec_pending() after the target io is done in .poll_bio() > > 5) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL, > which is based on Jeffle's previous patch. It's not the prettiest thing in the world with the overlay on bi_private, but at least it's nicely documented now. I would encourage you to actually test this on fast storage, should make a nice difference. I can run this on a gen2 optane, it's 10x the IOPS of what it was tested on and should help better highlight where it makes a difference. If either of you would like that, then send me a fool proof recipe for what should be setup so I have a poll capable dm device. -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
