From 380c3f2fc78c34aadac7678180c4c0080989f2ef Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Fri, 19 Mar 2021 17:22:30 +0000 Subject: [PATCH] io_uring: optimise io_uring_enter() Add unlikely annotations, because my compiler pretty much mispredicts every first check, and apart jumping around in the fast path, it also generates extra instructions, like in advance setting ret value. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- fs/io_uring.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 12e2ec7cfba4f..13a64b1db3bee 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -9183,31 +9183,31 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, size_t, argsz) { struct io_ring_ctx *ctx; - long ret = -EBADF; int submitted = 0; struct fd f; + long ret; io_run_task_work(); - if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP | - IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG)) + if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP | + IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG))) return -EINVAL; f = fdget(fd); - if (!f.file) + if (unlikely(!f.file)) return -EBADF; ret = -EOPNOTSUPP; - if (f.file->f_op != &io_uring_fops) + if (unlikely(f.file->f_op != &io_uring_fops)) goto out_fput; ret = -ENXIO; ctx = f.file->private_data; - if (!percpu_ref_tryget(&ctx->refs)) + if (unlikely(!percpu_ref_tryget(&ctx->refs))) goto out_fput; ret = -EBADFD; - if (ctx->flags & IORING_SETUP_R_DISABLED) + if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED)) goto out; /* -- 2.39.5