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| author | Pavel Begunkov <asml.silence@gmail.com> | 2023-01-23 14:37:19 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-29 15:17:41 -0700 |
| commit | 50470fc5723ae0adb2f429a8b27ff6bf1a41913e (patch) | |
| tree | 42773f2952bf87ce42ab1d4e4dfdb3fbb52daa32 /io_uring | |
| parent | cb6bf7f285c270d7808807128b5bce414e3f254a (diff) | |
| download | lwn-50470fc5723ae0adb2f429a8b27ff6bf1a41913e.tar.gz lwn-50470fc5723ae0adb2f429a8b27ff6bf1a41913e.zip | |
io_uring: return normal tw run linking optimisation
io_submit_flush_completions() may produce new task_work items, so it's a
good idea to recheck the task_work list after flushing completions. The
optimisation is not new and was accidentially removed by
f88262e60bb9 ("io_uring: lockless task list")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a7ed5ede84de190832cc33ebbcdd6e91cd90f5b6.1674484266.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 | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 55101013f3ee..9c92ca081c11 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1238,6 +1238,15 @@ void tctx_task_work(struct callback_head *cb) loops++; node = io_llist_xchg(&tctx->task_list, &fake); count += handle_tw_list(node, &ctx, &uring_locked, &fake); + + /* skip expensive cmpxchg if there are items in the list */ + if (READ_ONCE(tctx->task_list.first) != &fake) + continue; + if (uring_locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) { + io_submit_flush_completions(ctx); + if (READ_ONCE(tctx->task_list.first) != &fake) + continue; + } node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL); } while (node != &fake); |