Here is a revamped series on uring-passthru which is on top of Jens "nvme-passthru-wip.2" branch. https://git.kernel.dk/cgit/linux-block/commit/?h=nvme-passthru-wip.2 This scales much better than before with the addition of following: - plugging - passthru polling (sync and async; sync part comes from a patch that Keith did earlier) - bio-cache (this is regardless of irq/polling since we submit/complete in task-contex anyway. Currently kicks in when fixed-buffer option is also passed, but that's primarily to keep the plumbing simple) Also the feedback from Christoph (previous fixed-buffer series) is in which has streamlined the plumbing. I look forward to further feedback/comments. KIOPS(512b) on P5800x looked like this: QD uring pt uring-poll pt-poll 8 538 589 831 902 64 967 1131 1351 1378 256 1043 1230 1376 1429 Here uring is operating on block-interface (nvme0n1) while 'pt' refers to uring-passthru operating on char-interface (ng0n1). Perf/testing is with this custom fio that turnes regular io into passthru on supplying "uring_cmd=1" option. https://github.com/joshkan/fio/tree/nvme-passthru-wip-polling Example command-line: fio -iodepth=256 -rw=randread -ioengine=io_uring -bs=512 -numjobs=1 -runtime=60 -group_reporting -iodepth_batch_submit=64 -iodepth_batch_complete_min=1 -iodepth_batch_complete_max=64 -fixedbufs=1 -hipri=1 -sqthread_poll=0 -filename=/dev/ng0n1 -name=io_uring_256 -uring_cmd=1 background/context: https://linuxplumbersconf.org/event/11/contributions/989/attachments/747/1723/lpc-2021-building-a-fast-passthru.pdf Changes from v5: https://lore.kernel.org/linux-nvme/20210805125539.66958-1-joshi.k@xxxxxxxxxxx/ 1. Fixed-buffer passthru with same ioctl code + other feedback from hch 2. Plugging (from Jens) 3. Sync polling (from Keith) 3. Async polling via io_uring 4. Enable bio-cache for fixed-buffer passthru Changes from v4: https://lore.kernel.org/linux-nvme/20210325170540.59619-1-joshi.k@xxxxxxxxxxx/ 1. Moved to v5 branch of Jens, adapted to task-work changes in io_uring 2. Removed support for block-passthrough (over nvme0n1) for now 3. Added support for char-passthrough (over ng0n1) 4. Added fixed-buffer passthrough in io_uring and nvme plumbing Anuj Gupta (3): io_uring: mark iopoll not supported for uring-cmd io_uring: modify unused field in io_uring_cmd to store flags io_uring: add support for uring_cmd with fixed-buffer Jens Axboe (2): io_uring: plug for async bypass block: wire-up support for plugging Kanchan Joshi (6): io_uring: add infra for uring_cmd completion in submitter-task nvme: wire-up support for async-passthru on char-device. io_uring: add flag and helper for fixed-buffer uring-cmd nvme: enable passthrough with fixed-buffer block: factor out helper for bio allocation from cache nvme: enable bio-cache for fixed-buffer passthru Keith Busch (1): nvme: allow user passthrough commands to poll Pankaj Raghav (1): nvme: Add async passthru polling support block/bio.c | 43 +++-- block/blk-map.c | 46 ++++++ block/blk-mq.c | 93 +++++------ drivers/nvme/host/core.c | 21 ++- drivers/nvme/host/ioctl.c | 271 ++++++++++++++++++++++++++++---- drivers/nvme/host/multipath.c | 2 + drivers/nvme/host/nvme.h | 13 +- drivers/nvme/host/pci.c | 4 +- drivers/nvme/target/passthru.c | 2 +- fs/io_uring.c | 113 +++++++++++-- include/linux/bio.h | 1 + include/linux/blk-mq.h | 4 + include/linux/io_uring.h | 26 ++- include/uapi/linux/io_uring.h | 6 +- include/uapi/linux/nvme_ioctl.h | 4 + 15 files changed, 542 insertions(+), 107 deletions(-) -- 2.25.1
