[PATCH BUGFIX/IMPROVEMENT 3/6] block, bfq: fix switch back from soft-rt weitgh-raising
From: Paolo Valente <hidden>
Date: 2021-01-26 10:10:51
Also in:
lkml
Subsystem:
bfq i/o scheduler, block layer, the rest · Maintainers:
Yu Kuai, Jens Axboe, Linus Torvalds
A bfq_queue may happen to be deemed as soft real-time while it is still enjoying interactive weight-raising. If this happens because of a false positive, then the bfq_queue is likely to loose its soft real-time status soon. Upon losing such a status, the bfq_queue must get back its interactive weight-raising, if its interactive period is not over yet. But this case is not handled. This commit corrects this error. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <redacted> --- block/bfq-iosched.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 6a02a12ff553..9e5242b2788a 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c@@ -5293,8 +5293,26 @@ bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfqq->wr_coeff > 1 && bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && - BFQQ_TOTALLY_SEEKY(bfqq)) - bfq_bfqq_end_wr(bfqq); + BFQQ_TOTALLY_SEEKY(bfqq)) { + if (time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt + + bfq_wr_duration(bfqd))) { + /* + * In soft_rt weight raising with the + * interactive-weight-raising period + * elapsed (so no switch back to + * interactive weight raising). + */ + bfq_bfqq_end_wr(bfqq); + } else { /* + * stopping soft_rt weight raising + * while still in interactive period, + * switch back to interactive weight + * raising + */ + switch_back_to_interactive_wr(bfqq, bfqd); + bfqq->entity.prio_changed = 1; + } + } } static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
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2.20.1