diff options
| author | Max Kellermann <max.kellermann@ionos.com> | 2025-01-28 14:39:24 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-02-17 05:34:45 -0700 |
| commit | 486ba4d84d62e92716cd395c4b1612b8ce70a257 (patch) | |
| tree | f0f09b288dcf095f4a35742050125702f3effc75 | |
| parent | 6ee78354eaa602002448f098b34678396d99043d (diff) | |
io_uring/io-wq: do not use bogus hash value
Previously, the `hash` variable was initialized with `-1` and only
updated by io_get_next_work() if the current work was hashed. Commit
60cf46ae6054 ("io-wq: hash dependent work") changed this to always
call io_get_work_hash() even if the work was not hashed. This caused
the `hash != -1U` check to always be true, adding some overhead for
the `hash->wait` code.
This patch fixes the regression by checking the `IO_WQ_WORK_HASHED`
flag.
Perf diff for a flood of `IORING_OP_NOP` with `IOSQE_ASYNC`:
38.55% -1.57% [kernel.kallsyms] [k] queued_spin_lock_slowpath
6.86% -0.72% [kernel.kallsyms] [k] io_worker_handle_work
0.10% +0.67% [kernel.kallsyms] [k] put_prev_entity
1.96% +0.59% [kernel.kallsyms] [k] io_nop_prep
3.31% -0.51% [kernel.kallsyms] [k] try_to_wake_up
7.18% -0.47% [kernel.kallsyms] [k] io_wq_free_work
Fixes: 60cf46ae6054 ("io-wq: hash dependent work")
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/20250128133927.3989681-6-max.kellermann@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/io-wq.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index ba9974e6f5213..6e31f312b61a1 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -604,7 +604,9 @@ static void io_worker_handle_work(struct io_wq_acct *acct, do { struct io_wq_work *next_hashed, *linked; unsigned int work_flags = atomic_read(&work->flags); - unsigned int hash = __io_get_work_hash(work_flags); + unsigned int hash = __io_wq_is_hashed(work_flags) + ? __io_get_work_hash(work_flags) + : -1U; next_hashed = wq_next_work(work); |