On Sat 14-05-22 17:05:21, Yu Kuai wrote: > It will only be called from bfq_bfqq_handle_idle_busy_switch() in > specific code branch, there is no need to precaculate > 'bfqq_wants_to_preempt' each time bfq_bfqq_handle_idle_busy_switch() > is caleld. > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Please see below: > @@ -1816,14 +1807,6 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, > (bfqq->bic || RQ_BIC(rq)->stably_merged) && > (*interactive || soft_rt))); > > - /* > - * Using the last flag, update budget and check whether bfqq > - * may want to preempt the in-service queue. > - */ > - bfqq_wants_to_preempt = > - bfq_bfqq_update_budg_for_activation(bfqd, bfqq, > - arrived_in_time); > - > /* > * If bfqq happened to be activated in a burst, but has been > * idle for much more than an interactive queue, then we ... > @@ -1918,7 +1900,7 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, > * (2) this switch of bfqq to busy changes the scenario. > */ > if (bfqd->in_service_queue && > - ((bfqq_wants_to_preempt && > + ((bfq_bfqq_update_budg_for_activation(bfqd, bfqq) && > bfqq->wr_coeff >= bfqd->in_service_queue->wr_coeff) || > bfq_bfqq_higher_class_or_weight(bfqq, bfqd->in_service_queue) || > !bfq_better_to_idle(bfqd->in_service_queue)) && So these changes are actually wrong because bfq_bfqq_update_budg_for_activation() relies on bfq_bfqq_non_blocking_wait_rq() but bfq_add_bfqq_busy() clears that. And bfq_add_bfqq_busy() is called between the place where bfq_bfqq_update_budg_for_activation() was called previously and now so your patch breaks this logic. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
