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io_uring: pre-calculate syscall iopolling decision

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Syscall should only iopoll for events when it's a IOPOLL ring and is not
SQPOLL. Instead of check both flags every time we can save it in ring
flags so it's easier to use. We don't care much about an extra if there,
however it will be inconvenient to copy-paste this chunk with checks in
future patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7fd2f8fc2606305aa06dd8c0ff8f76a66b39c383.1647957378.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-03-22 14:07:57 +00:00 committed by Jens Axboe
parent f81440d33c
commit 773697b610
1 changed files with 13 additions and 8 deletions
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21
fs/io_uring.c
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@ -356,6 +356,7 @@ struct io_ring_ctx {
unsigned int drain_active: 1;
unsigned int drain_disabled: 1;
unsigned int has_evfd: 1;
unsigned int syscall_iopoll: 1;
} ____cacheline_aligned_in_smp;
/* submission data */
@ -10829,14 +10830,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
if (flags & IORING_ENTER_GETEVENTS) {
min_complete = min(min_complete, ctx->cq_entries);
/*
* When SETUP_IOPOLL and SETUP_SQPOLL are both enabled, user
* space applications don't need to do io completion events
* polling again, they can rely on io_sq_thread to do polling
* work, which can reduce cpu usage and uring_lock contention.
*/
if (ctx->flags & IORING_SETUP_IOPOLL &&
!(ctx->flags & IORING_SETUP_SQPOLL)) {
if (ctx->syscall_iopoll) {
ret = io_validate_ext_arg(flags, argp, argsz);
if (unlikely(ret))
goto out;
@ -11174,6 +11168,17 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
ctx = io_ring_ctx_alloc(p);
if (!ctx)
return -ENOMEM;
/*
* When SETUP_IOPOLL and SETUP_SQPOLL are both enabled, user
* space applications don't need to do io completion events
* polling again, they can rely on io_sq_thread to do polling
* work, which can reduce cpu usage and uring_lock contention.
*/
if (ctx->flags & IORING_SETUP_IOPOLL &&
!(ctx->flags & IORING_SETUP_SQPOLL))
ctx->syscall_iopoll = 1;
ctx->compat = in_compat_syscall();
if (!capable(CAP_IPC_LOCK))
ctx->user = get_uid(current_user());