Hi all, What's the latest progress of this bio-based polling feature?
I've noticed that hch has also sent a patch set on this [1]. But as far as I know, hch's patch set only refactors the interface of polling in the block layer. It indeed helps bio-based polling for some kind of bio-based driver, but for DM/MD where one bio could be mapped to several split bios, more work is obviously needed, just like Lei Ming's io_context related code in this patch set. hch may have better idea, after all [1] is just a preparation patch set. [1] https://lore.kernel.org/linux-block/[email protected]/T/ -- Thanks, Jeffle On 4/22/21 8:20 PM, Ming Lei wrote: > Hi Jens, > > Add per-task io poll context for holding HIPRI blk-mq/underlying bios > queued from bio based driver's io submission context, and reuse one bio > padding field for storing 'cookie' returned from submit_bio() for these > bios. Also explicitly end these bios in poll context by adding two > new bio flags. > > In this way, we needn't to poll all underlying hw queues any more, > which is implemented in Jeffle's patches. And we can just poll hw queues > in which there is HIPRI IO queued. > > Usually io submission and io poll share same context, so the added io > poll context data is just like one stack variable, and the cost for > saving bios is cheap. > > V6: > - move poll code into block/blk-poll.c, as suggested by Christoph > - define bvec_iter as __packed, and add one new field to bio, as > suggested by Christoph > - re-organize patch order, as suggested by Christoph > - add one flag for checking if the disk is capable of bio polling > and remove .poll_capable(), as suggested by Christoph > - fix type of .bi_poll > > V5: > - fix one use-after-free issue in case that polling is from another > context: adds one new cookie of BLK_QC_T_NOT_READY for preventing > this issue in patch 8/12 > - add reviewed-by & tested-by tag > > V4: > - cover one more test_bit(QUEUE_FLAG_POLL, ...) suggested by > Jeffle(01/12) > - drop patch of 'block: add helper of blk_create_io_context' > - add new helper of blk_create_io_poll_context() (03/12) > - drain submission queues in exit_io_context(), suggested by > Jeffle(08/13) > - considering shared io context case for blk_bio_poll_io_drain() > (08/13) > - fix one issue in blk_bio_poll_pack_groups() as suggested by > Jeffle(08/13) > - add reviewed-by tag > V3: > - fix cookie returned for bio based driver, as suggested by Jeffle Xu > - draining pending bios when submission context is exiting > - patch style and comment fix, as suggested by Mike > - allow poll context data to be NULL by always polling on submission > queue > - remove RFC, and reviewed-by > > V2: > - address queue depth scalability issue reported by Jeffle via bio > group list. Reuse .bi_end_io for linking bios which share same > .bi_end_io, and support 32 such groups in submit queue. With this way, > the scalability issue caused by kfifio is solved. Before really > ending bio, .bi_end_io is recovered from the group head. > > > > Jeffle Xu (2): > block: extract one helper function polling hw queue > dm: support IO polling for bio-based dm device > > Ming Lei (10): > block: add helper of blk_queue_poll > block: define 'struct bvec_iter' as packed > block: add one helper to free io_context > block: move block polling code into one dedicated source file > block: prepare for supporting bio_list via other link > block: create io poll context for submission and poll task > block: add req flag of REQ_POLL_CTX > block: use per-task poll context to implement bio based io polling > block: limit hw queues to be polled in each blk_poll() > block: allow to control FLAG_POLL via sysfs for bio poll capable queue > > block/Makefile | 3 +- > block/bio.c | 5 + > block/blk-core.c | 68 +++- > block/blk-ioc.c | 15 +- > block/blk-mq.c | 231 ------------- > block/blk-mq.h | 40 +++ > block/blk-poll.c | 632 ++++++++++++++++++++++++++++++++++ > block/blk-sysfs.c | 16 +- > block/blk.h | 112 ++++++ > drivers/md/dm-table.c | 24 ++ > drivers/md/dm.c | 2 + > drivers/nvme/host/core.c | 2 +- > include/linux/bio.h | 132 +++---- > include/linux/blk_types.h | 31 +- > include/linux/blkdev.h | 1 + > include/linux/bvec.h | 2 +- > include/linux/device-mapper.h | 1 + > include/linux/genhd.h | 2 + > include/linux/iocontext.h | 2 + > 19 files changed, 1003 insertions(+), 318 deletions(-) > create mode 100644 block/blk-poll.c > -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
