diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index cd307767a134..c7a4a15c7c19 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -3274,16 +3274,32 @@ void bfq_bfqq_expire(struct bfq_data *bfqd, * requests, then the request pattern is isochronous * (see the comments on the function * bfq_bfqq_softrt_next_start()). Thus we can compute - * soft_rt_next_start. If, instead, the queue still - * has outstanding requests, then we have to wait for - * the completion of all the outstanding requests to - * discover whether the request pattern is actually - * isochronous. + * soft_rt_next_start. And we do it, unless bfqq is in + * interactive weight raising. We do not do it in the + * latter subcase, for the following reason. bfqq may + * be conveying the I/O needed to load a soft + * real-time application. Such an application will + * actually exhibit a soft real-time I/O pattern after + * it finally starts doing its job. But, if + * soft_rt_next_start is computed here for an + * interactive bfqq, and bfqq had received a lot of + * service before remaining with no outstanding + * request (likely to happen on a fast device), then + * soft_rt_next_start would be assigned such a high + * value that, for a very long time, bfqq would be + * prevented from being possibly considered as soft + * real time. + * + * If, instead, the queue still has outstanding + * requests, then we have to wait for the completion + * of all the outstanding requests to discover whether + * the request pattern is actually isochronous. */ - if (bfqq->dispatched == 0) + if (bfqq->dispatched == 0 && + bfqq->wr_coeff != bfqd->bfq_wr_coeff) bfqq->soft_rt_next_start = bfq_bfqq_softrt_next_start(bfqd, bfqq); - else { + else if (bfqq->dispatched > 0) { /* * Schedule an update of soft_rt_next_start to when * the task may be discovered to be isochronous. @@ -4834,11 +4850,14 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd) * isochronous, and both requisites for this condition to hold * are now satisfied, then compute soft_rt_next_start (see the * comments on the function bfq_bfqq_softrt_next_start()). We - * schedule this delayed check when bfqq expires, if it still - * has in-flight requests. + * do not compute soft_rt_next_start if bfqq is in interactive + * weight raising (see the comments in bfq_bfqq_expire() for + * an explanation). We schedule this delayed update when bfqq + * expires, if it still has in-flight requests. */ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && - RB_EMPTY_ROOT(&bfqq->sort_list)) + RB_EMPTY_ROOT(&bfqq->sort_list) && + bfqq->wr_coeff != bfqd->bfq_wr_coeff) bfqq->soft_rt_next_start = bfq_bfqq_softrt_next_start(bfqd, bfqq); |