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[BUGFIX/IMPROVEMENT,4/6] block, bfq: do not raise non-default weights

Message ID 20210122181948.35660-5-paolo.valente@linaro.org (mailing list archive)
State New, archived
Headers show
Series block, bfq: first bath of fixes and improvements | expand

Commit Message

Paolo Valente Jan. 22, 2021, 6:19 p.m. UTC 
BFQ heuristics try to detect interactive I/O, and raise the weight of
the queues containing such an I/O. Yet, if also the user changes the
weight of a queue (i.e., the user changes the ioprio of the process
associated with that queue), then it is most likely better to prevent
BFQ heuristics from silently changing the same weight.

Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-iosched.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
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Patch

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 43e2c39cf7b5..161badb744d6 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1671,15 +1671,19 @@  static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
 	 * - it is sync,
 	 * - it does not belong to a large burst,
 	 * - it has been idle for enough time or is soft real-time,
-	 * - is linked to a bfq_io_cq (it is not shared in any sense).
+	 * - is linked to a bfq_io_cq (it is not shared in any sense),
+	 * - has a default weight (otherwise we assume the user wanted
+	 *   to control its weight explicitly)
 	 */
 	in_burst = bfq_bfqq_in_large_burst(bfqq);
 	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
 		!BFQQ_TOTALLY_SEEKY(bfqq) &&
 		!in_burst &&
 		time_is_before_jiffies(bfqq->soft_rt_next_start) &&
-		bfqq->dispatched == 0;
-	*interactive = !in_burst && idle_for_long_time;
+		bfqq->dispatched == 0 &&
+		bfqq->entity.new_weight == 40;
+	*interactive = !in_burst && idle_for_long_time &&
+		bfqq->entity.new_weight == 40;
 	wr_or_deserves_wr = bfqd->low_latency &&
 		(bfqq->wr_coeff > 1 ||
 		 (bfq_bfqq_sync(bfqq) &&