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io-wq: optimise out *next_work() double lock 

When executing non-linked hashed work, io_worker_handle_work()
will lock-unlock wqe->lock to update hash, and then immediately
lock-unlock to get next work. Optimise this case and do
lock/unlock only once.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-03-04 16:14:11 +03:00 committed by Jens Axboe
parent 58e3931987
commit f462fd36fc
1 changed files with 6 additions and 3 deletions
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9
fs/io-wq.c
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@ -474,11 +474,11 @@ static void io_worker_handle_work(struct io_worker *worker)
{
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
unsigned hash = -1U;
do {
struct io_wq_work *work;
unsigned hash = -1U;
get_next:
/*
* If we got some work, mark us as busy. If we didn't, but
* the list isn't empty, it means we stalled on hashed work.
@ -524,9 +524,12 @@ static void io_worker_handle_work(struct io_worker *worker)
spin_lock_irq(&wqe->lock);
wqe->hash_map &= ~BIT_ULL(hash);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
spin_unlock_irq(&wqe->lock);
/* dependent work is not hashed */
hash = -1U;
/* skip unnecessary unlock-lock wqe->lock */
if (!work)
goto get_next;
spin_unlock_irq(&wqe->lock);
}
} while (work);