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| author | Pavel Begunkov <asml.silence@gmail.com> | 2023-01-09 14:46:13 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-29 15:17:40 -0700 |
| commit | c3f4d39ee4bc06f975ff45012398342ff276eb69 (patch) | |
| tree | c9b87d65bcfa0cfb1161e63468cbe3de2b125c49 /io_uring | |
| parent | d80c0f00d04766972c95e72b7535a842d6f4680d (diff) | |
| download | linux-c3f4d39ee4bc06f975ff45012398342ff276eb69.tar.gz linux-c3f4d39ee4bc06f975ff45012398342ff276eb69.tar.bz2 linux-c3f4d39ee4bc06f975ff45012398342ff276eb69.zip | |
io_uring: optimise deferred tw execution
We needed fake nodes in __io_run_local_work() and to avoid unecessary wake
ups while the task already running task_works, but we don't need them
anymore since wake ups are protected by cq_waiting, which is always
cleared by the time we're executing deferred task_work items.
Note that because of loose sync around cq_waiting clearing
io_req_local_work_add() may wake the task more than once, but that's
fine and should be rare to not hurt perf.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8839534891f0a2f1076e78554a31ea7e099f7de5.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 24 |
1 files changed, 7 insertions, 17 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 3f92028a7ee8..653361746203 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1322,17 +1322,16 @@ static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx) static int __io_run_local_work(struct io_ring_ctx *ctx, bool *locked) { struct llist_node *node; - struct llist_node fake; - struct llist_node *current_final = NULL; + unsigned int loops = 0; int ret = 0; - unsigned int loops = 1; if (WARN_ON_ONCE(ctx->submitter_task != current)) return -EEXIST; - - node = io_llist_xchg(&ctx->work_llist, &fake); + if (ctx->flags & IORING_SETUP_TASKRUN_FLAG) + atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags); again: - while (node != current_final) { + node = io_llist_xchg(&ctx->work_llist, NULL); + while (node) { struct llist_node *next = node->next; struct io_kiocb *req = container_of(node, struct io_kiocb, io_task_work.node); @@ -1341,23 +1340,14 @@ again: ret++; node = next; } + loops++; - if (ctx->flags & IORING_SETUP_TASKRUN_FLAG) - atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags); - - node = io_llist_cmpxchg(&ctx->work_llist, &fake, NULL); - if (node != &fake) { - loops++; - current_final = &fake; - node = io_llist_xchg(&ctx->work_llist, &fake); + if (!llist_empty(&ctx->work_llist)) goto again; - } - if (*locked) io_submit_flush_completions(ctx); trace_io_uring_local_work_run(ctx, ret, loops); return ret; - } static inline int io_run_local_work_locked(struct io_ring_ctx *ctx) |