From: Pavel Begunkov Date: Mon, 4 Oct 2021 19:02:46 +0000 (+0100) Subject: io_uring: optimise kiocb layout X-Git-Tag: v6.6.17~9008^2~56 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7e3709d57651feab9c77d7a5a8024041f73f69f7;p=platform%2Fkernel%2Flinux-rpi.git io_uring: optimise kiocb layout We want ->comp_list in the second cacheline, which is hotter comparing to the 3rd. Swap the field with ->link, which is not as hot and controlled by flags and so not accessed unless there is a link. By the way add a couple of comments for io_kiocb fields. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/9d9dde31f8f62279a5f48c575bbc27b8290edc0c.1633373302.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- diff --git a/fs/io_uring.c b/fs/io_uring.c index 5b3b4f8..ab07a08 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -863,19 +863,22 @@ struct io_kiocb { struct task_struct *task; u64 user_data; - struct io_kiocb *link; struct percpu_ref *fixed_rsrc_refs; - /* used with ctx->iopoll_list with reads/writes */ + /* used by request caches, completion batching and iopoll */ struct io_wq_work_node comp_list; + struct io_kiocb *link; struct io_task_work io_task_work; /* for polled requests, i.e. IORING_OP_POLL_ADD and async armed poll */ struct hlist_node hash_node; + /* internal polling, see IORING_FEAT_FAST_POLL */ struct async_poll *apoll; /* store used ubuf, so we can prevent reloading */ struct io_mapped_ubuf *imu; struct io_wq_work work; + /* custom credentials, valid IFF REQ_F_CREDS is set */ const struct cred *creds; + /* stores selected buf, valid IFF REQ_F_BUFFER_SELECTED is set */ struct io_buffer *kbuf; };