On Tue 10-05-22 21:16:29, Yu Kuai wrote: > bfq_has_work() is using busy_queues currently, which is not accurate > because bfq_queue is busy doesn't represent that it has requests. Since > bfqd aready has a counter 'queued' to record how many requests are in > bfq, use it instead of busy_queues. > > Noted that bfq_has_work() can be called with 'bfqd->lock' held, thus the > lock can't be held in bfq_has_work() to protect 'bfqd->queued'. > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> So did you find this causing any real problem? Because bfq queue is accounted among busy queues once bfq_add_bfqq_busy() is called. And that happens once a new request is inserted into the queue so it should be very similar to bfqd->queued. Honza > --- > block/bfq-iosched.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index 61750696e87f..1d2f8110c26b 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -5063,11 +5063,11 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) > struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; > > /* > - * Avoiding lock: a race on bfqd->busy_queues should cause at > + * Avoiding lock: a race on bfqd->queued should cause at > * most a call to dispatch for nothing > */ > return !list_empty_careful(&bfqd->dispatch) || > - bfq_tot_busy_queues(bfqd) > 0; > + READ_ONCE(bfqd->queued); > } > > static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) > -- > 2.31.1 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
