| Message ID | 4b4e3526-e6b5-73dd-c6fb-f7ddccf19f33@kernel.dk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io_uring/uring_cmd: push IRQ based completions through task_work | expand |
On Sun, Mar 19, 2023 at 8:51 PM Jens Axboe <axboe@kernel.dk> wrote: > > This is similar to what we do on the non-passthrough read/write side, > and helps take advantage of the completion batching we can do when we > post CQEs via task_work. On top of that, this avoids a uring_lock > grab/drop for every completion. > > In the normal peak IRQ based testing, this increases performance in > my testing from ~75M to ~77M IOPS, or an increase of 2-3%. > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > --- > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 2e4c483075d3..b4fba5f0ab0d 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, > void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) > { > struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); > + struct io_ring_ctx *ctx = req->ctx; > > if (ret < 0) > req_set_fail(req); > > io_req_set_res(req, ret, 0); > - if (req->ctx->flags & IORING_SETUP_CQE32) > + if (ctx->flags & IORING_SETUP_CQE32) > io_req_set_cqe32_extra(req, res2, 0); > - if (req->ctx->flags & IORING_SETUP_IOPOLL) > + if (ctx->flags & IORING_SETUP_IOPOLL) { > /* order with io_iopoll_req_issued() checking ->iopoll_complete */ > smp_store_release(&req->iopoll_completed, 1); > - else > - io_req_complete_post(req, 0); > + return; > + } > + req->io_task_work.func = io_req_task_complete; > + io_req_task_work_add(req); > } Since io_uring_cmd_done itself would be executing in task-work often (always in case of nvme), can this be further optimized by doing directly what this new task-work (that is being set up here) would have done? Something like below on top of your patch - diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index e1929f6e5a24..7a764e04f309 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -58,8 +58,12 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) smp_store_release(&req->iopoll_completed, 1); return; } - req->io_task_work.func = io_req_task_complete; - io_req_task_work_add(req); + if (in_task()) { + io_req_complete_defer(req); + } else { + req->io_task_work.func = io_req_task_complete; + io_req_task_work_add(req); + } } EXPORT_SYMBOL_GPL(io_uring_cmd_done);
On 3/20/23 9:06?AM, Kanchan Joshi wrote: > On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: >> >> This is similar to what we do on the non-passthrough read/write side, >> and helps take advantage of the completion batching we can do when we >> post CQEs via task_work. On top of that, this avoids a uring_lock >> grab/drop for every completion. >> >> In the normal peak IRQ based testing, this increases performance in >> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. >> >> Signed-off-by: Jens Axboe <axboe@kernel.dk> >> >> --- >> >> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >> index 2e4c483075d3..b4fba5f0ab0d 100644 >> --- a/io_uring/uring_cmd.c >> +++ b/io_uring/uring_cmd.c >> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, >> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) >> { >> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); >> + struct io_ring_ctx *ctx = req->ctx; >> >> if (ret < 0) >> req_set_fail(req); >> >> io_req_set_res(req, ret, 0); >> - if (req->ctx->flags & IORING_SETUP_CQE32) >> + if (ctx->flags & IORING_SETUP_CQE32) >> io_req_set_cqe32_extra(req, res2, 0); >> - if (req->ctx->flags & IORING_SETUP_IOPOLL) >> + if (ctx->flags & IORING_SETUP_IOPOLL) { >> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ >> smp_store_release(&req->iopoll_completed, 1); >> - else >> - io_req_complete_post(req, 0); >> + return; >> + } >> + req->io_task_work.func = io_req_task_complete; >> + io_req_task_work_add(req); >> } > > Since io_uring_cmd_done itself would be executing in task-work often > (always in case of nvme), can this be further optimized by doing > directly what this new task-work (that is being set up here) would > have done? > Something like below on top of your patch - > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index e1929f6e5a24..7a764e04f309 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -58,8 +58,12 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, > ssize_t ret, ssize_t res2) > smp_store_release(&req->iopoll_completed, 1); > return; > } > - req->io_task_work.func = io_req_task_complete; > - io_req_task_work_add(req); > + if (in_task()) { > + io_req_complete_defer(req); > + } else { > + req->io_task_work.func = io_req_task_complete; > + io_req_task_work_add(req); > + } > } > EXPORT_SYMBOL_GPL(io_uring_cmd_done); Good point, though I do think we should rework to pass in the flags instead. I'll take a look.
On 3/20/23 2:03?PM, Jens Axboe wrote: > On 3/20/23 9:06?AM, Kanchan Joshi wrote: >> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: >>> >>> This is similar to what we do on the non-passthrough read/write side, >>> and helps take advantage of the completion batching we can do when we >>> post CQEs via task_work. On top of that, this avoids a uring_lock >>> grab/drop for every completion. >>> >>> In the normal peak IRQ based testing, this increases performance in >>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. >>> >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>> >>> --- >>> >>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >>> index 2e4c483075d3..b4fba5f0ab0d 100644 >>> --- a/io_uring/uring_cmd.c >>> +++ b/io_uring/uring_cmd.c >>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, >>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) >>> { >>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); >>> + struct io_ring_ctx *ctx = req->ctx; >>> >>> if (ret < 0) >>> req_set_fail(req); >>> >>> io_req_set_res(req, ret, 0); >>> - if (req->ctx->flags & IORING_SETUP_CQE32) >>> + if (ctx->flags & IORING_SETUP_CQE32) >>> io_req_set_cqe32_extra(req, res2, 0); >>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) >>> + if (ctx->flags & IORING_SETUP_IOPOLL) { >>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ >>> smp_store_release(&req->iopoll_completed, 1); >>> - else >>> - io_req_complete_post(req, 0); >>> + return; >>> + } >>> + req->io_task_work.func = io_req_task_complete; >>> + io_req_task_work_add(req); >>> } >> >> Since io_uring_cmd_done itself would be executing in task-work often >> (always in case of nvme), can this be further optimized by doing >> directly what this new task-work (that is being set up here) would >> have done? >> Something like below on top of your patch - >> >> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >> index e1929f6e5a24..7a764e04f309 100644 >> --- a/io_uring/uring_cmd.c >> +++ b/io_uring/uring_cmd.c >> @@ -58,8 +58,12 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, >> ssize_t ret, ssize_t res2) >> smp_store_release(&req->iopoll_completed, 1); >> return; >> } >> - req->io_task_work.func = io_req_task_complete; >> - io_req_task_work_add(req); >> + if (in_task()) { >> + io_req_complete_defer(req); >> + } else { >> + req->io_task_work.func = io_req_task_complete; >> + io_req_task_work_add(req); >> + } >> } >> EXPORT_SYMBOL_GPL(io_uring_cmd_done); > > Good point, though I do think we should rework to pass in the flags > instead. I'll take a look. Something like this, totally untested... And this may be more interesting than it would appear, because the current: io_req_complete_post(req, 0); in io_uring_cmd_done() is passing in that it has the CQ ring locked, but that does not look like it's guaranteed? So this is more of a correctness thing first and foremost, more so than an optimization. Hmm? diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index d1d1c8d606c8..6615986e976c 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -715,7 +715,7 @@ static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io, } } -static void ubq_complete_io_cmd(struct ublk_io *io, int res) +static void ubq_complete_io_cmd(struct ublk_io *io, int res, unsigned flags) { /* mark this cmd owned by ublksrv */ io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; @@ -727,7 +727,7 @@ static void ubq_complete_io_cmd(struct ublk_io *io, int res) io->flags &= ~UBLK_IO_FLAG_ACTIVE; /* tell ublksrv one io request is coming */ - io_uring_cmd_done(io->cmd, res, 0); + io_uring_cmd_done(io->cmd, res, 0, flags); } #define UBLK_REQUEUE_DELAY_MS 3 @@ -744,7 +744,7 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq, mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0); } -static inline void __ublk_rq_task_work(struct request *req) +static inline void __ublk_rq_task_work(struct request *req, unsigned issue_flags) { struct ublk_queue *ubq = req->mq_hctx->driver_data; int tag = req->tag; @@ -782,7 +782,7 @@ static inline void __ublk_rq_task_work(struct request *req) pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n", __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags); - ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA); + ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA, issue_flags); return; } /* @@ -820,17 +820,17 @@ static inline void __ublk_rq_task_work(struct request *req) mapped_bytes >> 9; } - ubq_complete_io_cmd(io, UBLK_IO_RES_OK); + ubq_complete_io_cmd(io, UBLK_IO_RES_OK, issue_flags); } -static inline void ublk_forward_io_cmds(struct ublk_queue *ubq) +static inline void ublk_forward_io_cmds(struct ublk_queue *ubq, unsigned flags) { struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds); struct ublk_rq_data *data, *tmp; io_cmds = llist_reverse_order(io_cmds); llist_for_each_entry_safe(data, tmp, io_cmds, node) - __ublk_rq_task_work(blk_mq_rq_from_pdu(data)); + __ublk_rq_task_work(blk_mq_rq_from_pdu(data), flags); } static inline void ublk_abort_io_cmds(struct ublk_queue *ubq) @@ -842,12 +842,12 @@ static inline void ublk_abort_io_cmds(struct ublk_queue *ubq) __ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data)); } -static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd) +static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd, unsigned issue_flags) { struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); struct ublk_queue *ubq = pdu->ubq; - ublk_forward_io_cmds(ubq); + ublk_forward_io_cmds(ubq, issue_flags); } static void ublk_rq_task_work_fn(struct callback_head *work) @@ -856,8 +856,9 @@ static void ublk_rq_task_work_fn(struct callback_head *work) struct ublk_rq_data, work); struct request *req = blk_mq_rq_from_pdu(data); struct ublk_queue *ubq = req->mq_hctx->driver_data; + unsigned issue_flags = IO_URING_F_UNLOCKED; - ublk_forward_io_cmds(ubq); + ublk_forward_io_cmds(ubq, issue_flags); } static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq) @@ -1111,7 +1112,8 @@ static void ublk_cancel_queue(struct ublk_queue *ubq) struct ublk_io *io = &ubq->ios[i]; if (io->flags & UBLK_IO_FLAG_ACTIVE) - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0); + io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, + IO_URING_F_UNLOCKED); } /* all io commands are canceled */ @@ -1351,7 +1353,7 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) return -EIOCBQUEUED; out: - io_uring_cmd_done(cmd, ret, 0); + io_uring_cmd_done(cmd, ret, 0, issue_flags); pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n", __func__, cmd_op, tag, ret, io->flags); return -EIOCBQUEUED; @@ -2233,7 +2235,7 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, if (ub) ublk_put_device(ub); out: - io_uring_cmd_done(cmd, ret, 0); + io_uring_cmd_done(cmd, ret, 0, issue_flags); pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n", __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id); return -EIOCBQUEUED; diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c index 723e7d5b778f..fd547b81d1d2 100644 --- a/drivers/nvme/host/ioctl.c +++ b/drivers/nvme/host/ioctl.c @@ -464,7 +464,7 @@ static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu( return (struct nvme_uring_cmd_pdu *)&ioucmd->pdu; } -static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd) +static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd, unsigned flags) { struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd); struct request *req = pdu->req; @@ -485,17 +485,17 @@ static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd) blk_rq_unmap_user(req->bio); blk_mq_free_request(req); - io_uring_cmd_done(ioucmd, status, result); + io_uring_cmd_done(ioucmd, status, result, flags); } -static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd) +static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd, unsigned flags) { struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd); if (pdu->bio) blk_rq_unmap_user(pdu->bio); - io_uring_cmd_done(ioucmd, pdu->nvme_status, pdu->u.result); + io_uring_cmd_done(ioucmd, pdu->nvme_status, pdu->u.result, flags); } static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req, @@ -517,7 +517,7 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req, * Otherwise, move the completion to task work. */ if (cookie != NULL && blk_rq_is_poll(req)) - nvme_uring_task_cb(ioucmd); + nvme_uring_task_cb(ioucmd, IO_URING_F_UNLOCKED); else io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb); @@ -539,7 +539,7 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io_meta(struct request *req, * Otherwise, move the completion to task work. */ if (cookie != NULL && blk_rq_is_poll(req)) - nvme_uring_task_meta_cb(ioucmd); + nvme_uring_task_meta_cb(ioucmd, IO_URING_F_UNLOCKED); else io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_meta_cb); diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h index 934e5dd4ccc0..562453edff69 100644 --- a/include/linux/io_uring.h +++ b/include/linux/io_uring.h @@ -27,7 +27,7 @@ struct io_uring_cmd { const void *cmd; union { /* callback to defer completions to task context */ - void (*task_work_cb)(struct io_uring_cmd *cmd); + void (*task_work_cb)(struct io_uring_cmd *cmd, unsigned); /* used for polled completion */ void *cookie; }; @@ -39,9 +39,10 @@ struct io_uring_cmd { #if defined(CONFIG_IO_URING) int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, struct iov_iter *iter, void *ioucmd); -void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2); +void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2, + unsigned issue_flags); void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd, - void (*task_work_cb)(struct io_uring_cmd *)); + void (*task_work_cb)(struct io_uring_cmd *, unsigned)); struct sock *io_uring_get_socket(struct file *file); void __io_uring_cancel(bool cancel_all); void __io_uring_free(struct task_struct *tsk); @@ -72,11 +73,11 @@ static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, return -EOPNOTSUPP; } static inline void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, - ssize_t ret2) + ssize_t ret2, bool *locked) { } static inline void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd, - void (*task_work_cb)(struct io_uring_cmd *)) + void (*task_work_cb)(struct io_uring_cmd *, unsigned)) { } static inline struct sock *io_uring_get_socket(struct file *file) diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index 2e4c483075d3..9a1dee571872 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -15,12 +15,13 @@ static void io_uring_cmd_work(struct io_kiocb *req, bool *locked) { struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); + unsigned issue_flags = *locked ? 0 : IO_URING_F_UNLOCKED; - ioucmd->task_work_cb(ioucmd); + ioucmd->task_work_cb(ioucmd, issue_flags); } void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd, - void (*task_work_cb)(struct io_uring_cmd *)) + void (*task_work_cb)(struct io_uring_cmd *, unsigned)) { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); @@ -42,7 +43,8 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, * Called by consumers of io_uring_cmd, if they originally returned * -EIOCBQUEUED upon receiving the command. */ -void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) +void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2, + unsigned issue_flags) { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); @@ -56,7 +58,7 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) /* order with io_iopoll_req_issued() checking ->iopoll_complete */ smp_store_release(&req->iopoll_completed, 1); else - io_req_complete_post(req, 0); + io_req_complete_post(req, issue_flags); } EXPORT_SYMBOL_GPL(io_uring_cmd_done);
On Mon, Mar 20, 2023 at 08:36:15PM +0530, Kanchan Joshi wrote: > On Sun, Mar 19, 2023 at 8:51 PM Jens Axboe <axboe@kernel.dk> wrote: > > > > This is similar to what we do on the non-passthrough read/write side, > > and helps take advantage of the completion batching we can do when we > > post CQEs via task_work. On top of that, this avoids a uring_lock > > grab/drop for every completion. > > > > In the normal peak IRQ based testing, this increases performance in > > my testing from ~75M to ~77M IOPS, or an increase of 2-3%. > > > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > > > --- > > > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > > index 2e4c483075d3..b4fba5f0ab0d 100644 > > --- a/io_uring/uring_cmd.c > > +++ b/io_uring/uring_cmd.c > > @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, > > void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) > > { > > struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); > > + struct io_ring_ctx *ctx = req->ctx; > > > > if (ret < 0) > > req_set_fail(req); > > > > io_req_set_res(req, ret, 0); > > - if (req->ctx->flags & IORING_SETUP_CQE32) > > + if (ctx->flags & IORING_SETUP_CQE32) > > io_req_set_cqe32_extra(req, res2, 0); > > - if (req->ctx->flags & IORING_SETUP_IOPOLL) > > + if (ctx->flags & IORING_SETUP_IOPOLL) { > > /* order with io_iopoll_req_issued() checking ->iopoll_complete */ > > smp_store_release(&req->iopoll_completed, 1); > > - else > > - io_req_complete_post(req, 0); > > + return; > > + } > > + req->io_task_work.func = io_req_task_complete; > > + io_req_task_work_add(req); > > } > > Since io_uring_cmd_done itself would be executing in task-work often > (always in case of nvme), can this be further optimized by doing > directly what this new task-work (that is being set up here) would > have done? > Something like below on top of your patch - But we have io_uring_cmd_complete_in_task() already, just wondering why not let driver decide if explicit running in task-work is taken? Thanks, Ming
On 3/20/23 5:35?PM, Ming Lei wrote: > On Mon, Mar 20, 2023 at 08:36:15PM +0530, Kanchan Joshi wrote: >> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: >>> >>> This is similar to what we do on the non-passthrough read/write side, >>> and helps take advantage of the completion batching we can do when we >>> post CQEs via task_work. On top of that, this avoids a uring_lock >>> grab/drop for every completion. >>> >>> In the normal peak IRQ based testing, this increases performance in >>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. >>> >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>> >>> --- >>> >>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >>> index 2e4c483075d3..b4fba5f0ab0d 100644 >>> --- a/io_uring/uring_cmd.c >>> +++ b/io_uring/uring_cmd.c >>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, >>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) >>> { >>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); >>> + struct io_ring_ctx *ctx = req->ctx; >>> >>> if (ret < 0) >>> req_set_fail(req); >>> >>> io_req_set_res(req, ret, 0); >>> - if (req->ctx->flags & IORING_SETUP_CQE32) >>> + if (ctx->flags & IORING_SETUP_CQE32) >>> io_req_set_cqe32_extra(req, res2, 0); >>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) >>> + if (ctx->flags & IORING_SETUP_IOPOLL) { >>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ >>> smp_store_release(&req->iopoll_completed, 1); >>> - else >>> - io_req_complete_post(req, 0); >>> + return; >>> + } >>> + req->io_task_work.func = io_req_task_complete; >>> + io_req_task_work_add(req); >>> } >> >> Since io_uring_cmd_done itself would be executing in task-work often >> (always in case of nvme), can this be further optimized by doing >> directly what this new task-work (that is being set up here) would >> have done? >> Something like below on top of your patch - > > But we have io_uring_cmd_complete_in_task() already, just wondering why > not let driver decide if explicit running in task-work is taken? Because it's currently broken, see my patch from earlier today.
On Mon, Mar 20, 2023 at 07:39:30PM -0600, Jens Axboe wrote: > On 3/20/23 5:35?PM, Ming Lei wrote: > > On Mon, Mar 20, 2023 at 08:36:15PM +0530, Kanchan Joshi wrote: > >> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: > >>> > >>> This is similar to what we do on the non-passthrough read/write side, > >>> and helps take advantage of the completion batching we can do when we > >>> post CQEs via task_work. On top of that, this avoids a uring_lock > >>> grab/drop for every completion. > >>> > >>> In the normal peak IRQ based testing, this increases performance in > >>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. > >>> > >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> > >>> > >>> --- > >>> > >>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > >>> index 2e4c483075d3..b4fba5f0ab0d 100644 > >>> --- a/io_uring/uring_cmd.c > >>> +++ b/io_uring/uring_cmd.c > >>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, > >>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) > >>> { > >>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); > >>> + struct io_ring_ctx *ctx = req->ctx; > >>> > >>> if (ret < 0) > >>> req_set_fail(req); > >>> > >>> io_req_set_res(req, ret, 0); > >>> - if (req->ctx->flags & IORING_SETUP_CQE32) > >>> + if (ctx->flags & IORING_SETUP_CQE32) > >>> io_req_set_cqe32_extra(req, res2, 0); > >>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) > >>> + if (ctx->flags & IORING_SETUP_IOPOLL) { > >>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ > >>> smp_store_release(&req->iopoll_completed, 1); > >>> - else > >>> - io_req_complete_post(req, 0); > >>> + return; > >>> + } > >>> + req->io_task_work.func = io_req_task_complete; > >>> + io_req_task_work_add(req); > >>> } > >> > >> Since io_uring_cmd_done itself would be executing in task-work often > >> (always in case of nvme), can this be further optimized by doing > >> directly what this new task-work (that is being set up here) would > >> have done? > >> Something like below on top of your patch - > > > > But we have io_uring_cmd_complete_in_task() already, just wondering why > > not let driver decide if explicit running in task-work is taken? > > Because it's currently broken, see my patch from earlier today. OK, got it, just miss your revised patch. Then I guess your patch needs to split into one bug fix(for backporting) on io_uring_cmd_done() and one optimization? thanks, Ming
On 3/20/23 7:54?PM, Ming Lei wrote: > On Mon, Mar 20, 2023 at 07:39:30PM -0600, Jens Axboe wrote: >> On 3/20/23 5:35?PM, Ming Lei wrote: >>> On Mon, Mar 20, 2023 at 08:36:15PM +0530, Kanchan Joshi wrote: >>>> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: >>>>> >>>>> This is similar to what we do on the non-passthrough read/write side, >>>>> and helps take advantage of the completion batching we can do when we >>>>> post CQEs via task_work. On top of that, this avoids a uring_lock >>>>> grab/drop for every completion. >>>>> >>>>> In the normal peak IRQ based testing, this increases performance in >>>>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. >>>>> >>>>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>>>> >>>>> --- >>>>> >>>>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >>>>> index 2e4c483075d3..b4fba5f0ab0d 100644 >>>>> --- a/io_uring/uring_cmd.c >>>>> +++ b/io_uring/uring_cmd.c >>>>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, >>>>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) >>>>> { >>>>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); >>>>> + struct io_ring_ctx *ctx = req->ctx; >>>>> >>>>> if (ret < 0) >>>>> req_set_fail(req); >>>>> >>>>> io_req_set_res(req, ret, 0); >>>>> - if (req->ctx->flags & IORING_SETUP_CQE32) >>>>> + if (ctx->flags & IORING_SETUP_CQE32) >>>>> io_req_set_cqe32_extra(req, res2, 0); >>>>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) >>>>> + if (ctx->flags & IORING_SETUP_IOPOLL) { >>>>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ >>>>> smp_store_release(&req->iopoll_completed, 1); >>>>> - else >>>>> - io_req_complete_post(req, 0); >>>>> + return; >>>>> + } >>>>> + req->io_task_work.func = io_req_task_complete; >>>>> + io_req_task_work_add(req); >>>>> } >>>> >>>> Since io_uring_cmd_done itself would be executing in task-work often >>>> (always in case of nvme), can this be further optimized by doing >>>> directly what this new task-work (that is being set up here) would >>>> have done? >>>> Something like below on top of your patch - >>> >>> But we have io_uring_cmd_complete_in_task() already, just wondering why >>> not let driver decide if explicit running in task-work is taken? >> >> Because it's currently broken, see my patch from earlier today. > > OK, got it, just miss your revised patch. > > Then I guess your patch needs to split into one bug fix(for backporting) on > io_uring_cmd_done() and one optimization? Yep, I think the backport fix patch actually takes care of most of it. So it'll just be a tweak on top, if anything. I'll send it out shortly so we can get it into 6.3.
On Tue, Mar 21, 2023 at 2:12 AM Jens Axboe <axboe@kernel.dk> wrote: > > On 3/20/23 2:03?PM, Jens Axboe wrote: > > On 3/20/23 9:06?AM, Kanchan Joshi wrote: > >> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: > >>> > >>> This is similar to what we do on the non-passthrough read/write side, > >>> and helps take advantage of the completion batching we can do when we > >>> post CQEs via task_work. On top of that, this avoids a uring_lock > >>> grab/drop for every completion. > >>> > >>> In the normal peak IRQ based testing, this increases performance in > >>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. > >>> > >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> > >>> > >>> --- > >>> > >>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > >>> index 2e4c483075d3..b4fba5f0ab0d 100644 > >>> --- a/io_uring/uring_cmd.c > >>> +++ b/io_uring/uring_cmd.c > >>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, > >>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) > >>> { > >>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); > >>> + struct io_ring_ctx *ctx = req->ctx; > >>> > >>> if (ret < 0) > >>> req_set_fail(req); > >>> > >>> io_req_set_res(req, ret, 0); > >>> - if (req->ctx->flags & IORING_SETUP_CQE32) > >>> + if (ctx->flags & IORING_SETUP_CQE32) > >>> io_req_set_cqe32_extra(req, res2, 0); > >>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) > >>> + if (ctx->flags & IORING_SETUP_IOPOLL) { > >>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ > >>> smp_store_release(&req->iopoll_completed, 1); > >>> - else > >>> - io_req_complete_post(req, 0); > >>> + return; > >>> + } > >>> + req->io_task_work.func = io_req_task_complete; > >>> + io_req_task_work_add(req); > >>> } > >> > >> Since io_uring_cmd_done itself would be executing in task-work often > >> (always in case of nvme), can this be further optimized by doing > >> directly what this new task-work (that is being set up here) would > >> have done? > >> Something like below on top of your patch - > >> > >> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > >> index e1929f6e5a24..7a764e04f309 100644 > >> --- a/io_uring/uring_cmd.c > >> +++ b/io_uring/uring_cmd.c > >> @@ -58,8 +58,12 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, > >> ssize_t ret, ssize_t res2) > >> smp_store_release(&req->iopoll_completed, 1); > >> return; > >> } > >> - req->io_task_work.func = io_req_task_complete; > >> - io_req_task_work_add(req); > >> + if (in_task()) { > >> + io_req_complete_defer(req); > >> + } else { > >> + req->io_task_work.func = io_req_task_complete; > >> + io_req_task_work_add(req); > >> + } > >> } > >> EXPORT_SYMBOL_GPL(io_uring_cmd_done); > > > > Good point, though I do think we should rework to pass in the flags > > instead. I'll take a look. > > Something like this, totally untested... And this may be more > interesting than it would appear, because the current: > > io_req_complete_post(req, 0); > > in io_uring_cmd_done() is passing in that it has the CQ ring locked, but > that does not look like it's guaranteed? So this is more of a > correctness thing first and foremost, more so than an optimization. > > Hmm? When zero is passed to io_req_complete_post, it calls __io_req_complete_post() which takes CQ lock as the first thing. So the correct thing will happen. Am I missing something?
On Tue, Mar 21, 2023 at 10:02 AM Kanchan Joshi <joshiiitr@gmail.com> wrote: > > On Tue, Mar 21, 2023 at 2:12 AM Jens Axboe <axboe@kernel.dk> wrote: > > > > On 3/20/23 2:03?PM, Jens Axboe wrote: > > > On 3/20/23 9:06?AM, Kanchan Joshi wrote: > > >> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: > > >>> > > >>> This is similar to what we do on the non-passthrough read/write side, > > >>> and helps take advantage of the completion batching we can do when we > > >>> post CQEs via task_work. On top of that, this avoids a uring_lock > > >>> grab/drop for every completion. > > >>> > > >>> In the normal peak IRQ based testing, this increases performance in > > >>> my testing from ~75M to ~77M IOPS, or an increase of 2-3%. > > >>> > > >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> > > >>> > > >>> --- > > >>> > > >>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > > >>> index 2e4c483075d3..b4fba5f0ab0d 100644 > > >>> --- a/io_uring/uring_cmd.c > > >>> +++ b/io_uring/uring_cmd.c > > >>> @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, > > >>> void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) > > >>> { > > >>> struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); > > >>> + struct io_ring_ctx *ctx = req->ctx; > > >>> > > >>> if (ret < 0) > > >>> req_set_fail(req); > > >>> > > >>> io_req_set_res(req, ret, 0); > > >>> - if (req->ctx->flags & IORING_SETUP_CQE32) > > >>> + if (ctx->flags & IORING_SETUP_CQE32) > > >>> io_req_set_cqe32_extra(req, res2, 0); > > >>> - if (req->ctx->flags & IORING_SETUP_IOPOLL) > > >>> + if (ctx->flags & IORING_SETUP_IOPOLL) { > > >>> /* order with io_iopoll_req_issued() checking ->iopoll_complete */ > > >>> smp_store_release(&req->iopoll_completed, 1); > > >>> - else > > >>> - io_req_complete_post(req, 0); > > >>> + return; > > >>> + } > > >>> + req->io_task_work.func = io_req_task_complete; > > >>> + io_req_task_work_add(req); > > >>> } > > >> > > >> Since io_uring_cmd_done itself would be executing in task-work often > > >> (always in case of nvme), can this be further optimized by doing > > >> directly what this new task-work (that is being set up here) would > > >> have done? > > >> Something like below on top of your patch - > > >> > > >> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > > >> index e1929f6e5a24..7a764e04f309 100644 > > >> --- a/io_uring/uring_cmd.c > > >> +++ b/io_uring/uring_cmd.c > > >> @@ -58,8 +58,12 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, > > >> ssize_t ret, ssize_t res2) > > >> smp_store_release(&req->iopoll_completed, 1); > > >> return; > > >> } > > >> - req->io_task_work.func = io_req_task_complete; > > >> - io_req_task_work_add(req); > > >> + if (in_task()) { > > >> + io_req_complete_defer(req); > > >> + } else { > > >> + req->io_task_work.func = io_req_task_complete; > > >> + io_req_task_work_add(req); > > >> + } > > >> } > > >> EXPORT_SYMBOL_GPL(io_uring_cmd_done); > > > > > > Good point, though I do think we should rework to pass in the flags > > > instead. I'll take a look. > > > > Something like this, totally untested... And this may be more > > interesting than it would appear, because the current: > > > > io_req_complete_post(req, 0); > > > > in io_uring_cmd_done() is passing in that it has the CQ ring locked, but > > that does not look like it's guaranteed? So this is more of a > > correctness thing first and foremost, more so than an optimization. > > > > Hmm? > > When zero is passed to io_req_complete_post, it calls > __io_req_complete_post() which takes CQ lock as the first thing. > So the correct thing will happen. Am I missing something? And because this CQ lock was there, optimization is able to improve the numbers.
On 3/20/23 20:42, Jens Axboe wrote: > On 3/20/23 2:03?PM, Jens Axboe wrote: >> On 3/20/23 9:06?AM, Kanchan Joshi wrote: >>> On Sun, Mar 19, 2023 at 8:51?PM Jens Axboe <axboe@kernel.dk> wrote: >>>> >>>> This is similar to what we do on the non-passthrough read/write side, >>>> and helps take advantage of the completion batching we can do when we >>>> post CQEs via task_work. On top of that, this avoids a uring_lock >>>> grab/drop for every completion. What we should do is to pass in "bool *locked" that we use for normal tw. I'll prep a patch converting that locked into a structure. I'd also argue it's better to use tw from commands directly without a second callback. That would need a couple of helpers.
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index 2e4c483075d3..b4fba5f0ab0d 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -45,18 +45,21 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req, void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2) { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); + struct io_ring_ctx *ctx = req->ctx; if (ret < 0) req_set_fail(req); io_req_set_res(req, ret, 0); - if (req->ctx->flags & IORING_SETUP_CQE32) + if (ctx->flags & IORING_SETUP_CQE32) io_req_set_cqe32_extra(req, res2, 0); - if (req->ctx->flags & IORING_SETUP_IOPOLL) + if (ctx->flags & IORING_SETUP_IOPOLL) { /* order with io_iopoll_req_issued() checking ->iopoll_complete */ smp_store_release(&req->iopoll_completed, 1); - else - io_req_complete_post(req, 0); + return; + } + req->io_task_work.func = io_req_task_complete; + io_req_task_work_add(req); } EXPORT_SYMBOL_GPL(io_uring_cmd_done);
This is similar to what we do on the non-passthrough read/write side, and helps take advantage of the completion batching we can do when we post CQEs via task_work. On top of that, this avoids a uring_lock grab/drop for every completion. In the normal peak IRQ based testing, this increases performance in my testing from ~75M to ~77M IOPS, or an increase of 2-3%. Signed-off-by: Jens Axboe <axboe@kernel.dk> ---