diff options
| author | Jens Axboe <axboe@kernel.dk> | 2020-02-25 08:47:30 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-02-25 08:57:37 -0700 |
| commit | 3030fd4cb783377eca0e2a3eee63724a5c66ee15 (patch) | |
| tree | 6949a688812bbf7a87aaea690873598364e4eb2a /fs | |
| parent | bdcd3eab2a9ae0ac93f27275b6895dd95e5bf360 (diff) | |
io-wq: remove spin-for-work optimization
Andres reports that buffered IO seems to suck up more cycles than we
would like, and he narrowed it down to the fact that the io-wq workers
will briefly spin for more work on completion of a work item. This was
a win on the networking side, but apparently some other cases take a
hit because of it. Remove the optimization to avoid burning more CPU
than we have to for disk IO.
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io-wq.c | 19 |
1 files changed, 0 insertions, 19 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c index 0a5ab1a8f69a..bf8ed1b0b90a 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -535,42 +535,23 @@ next: } while (1); } -static inline void io_worker_spin_for_work(struct io_wqe *wqe) -{ - int i = 0; - - while (++i < 1000) { - if (io_wqe_run_queue(wqe)) - break; - if (need_resched()) - break; - cpu_relax(); - } -} - static int io_wqe_worker(void *data) { struct io_worker *worker = data; struct io_wqe *wqe = worker->wqe; struct io_wq *wq = wqe->wq; - bool did_work; io_worker_start(wqe, worker); - did_work = false; while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) { set_current_state(TASK_INTERRUPTIBLE); loop: - if (did_work) - io_worker_spin_for_work(wqe); spin_lock_irq(&wqe->lock); if (io_wqe_run_queue(wqe)) { __set_current_state(TASK_RUNNING); io_worker_handle_work(worker); - did_work = true; goto loop; } - did_work = false; /* drops the lock on success, retry */ if (__io_worker_idle(wqe, worker)) { __release(&wqe->lock); |