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io_uring: optimise io_uring_enter()

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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 <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-03-19 17:22:30 +00:00 committed by Jens Axboe
parent 493f3b158a
commit 33f993da98
1 changed files with 7 additions and 7 deletions
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14
fs/io_uring.c
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@ -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;
/*