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From: Jan Kara <jack@suse.cz>
To: Jens Axboe <axboe@kernel.dk>
Cc: <linux-block@vger.kernel.org>,
	Paolo Valente <paolo.valente@linaro.org>, Jan Kara <jack@suse.cz>
Subject: [PATCH 7/8] bfq: Log waker detections
Date: Tue, 23 Nov 2021 11:29:19 +0100	[thread overview]
Message-ID: <20211123103158.17284-7-jack@suse.cz> (raw)
In-Reply-To: <20211123101109.20879-1-jack@suse.cz>

Waker - wakee relationships are important in deciding whether one queue
can preempt the other one. Print information about detected waker-wakee
relationships so that scheduling decisions can be better understood from
block traces.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 block/bfq-iosched.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 73eab70cefdb..3f1c8a080b71 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2127,6 +2127,8 @@ static void bfq_update_io_intensity(struct bfq_queue *bfqq, u64 now_ns)
 static void bfq_check_waker(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 			    u64 now_ns)
 {
+	char waker_name[MAX_BFQQ_NAME_LENGTH];
+
 	if (!bfqd->last_completed_rq_bfqq ||
 	    bfqd->last_completed_rq_bfqq == bfqq ||
 	    bfq_bfqq_has_short_ttime(bfqq) ||
@@ -2154,12 +2156,18 @@ static void bfq_check_waker(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 			bfqd->last_completed_rq_bfqq;
 		bfqq->num_waker_detections = 1;
 		bfqq->waker_detection_started = now_ns;
+		bfq_bfqq_name(bfqq->tentative_waker_bfqq, waker_name,
+			      MAX_BFQQ_NAME_LENGTH);
+		bfq_log_bfqq(bfqd, bfqq, "set tenative waker %s", waker_name);
 	} else /* Same tentative waker queue detected again */
 		bfqq->num_waker_detections++;
 
 	if (bfqq->num_waker_detections == 3) {
 		bfqq->waker_bfqq = bfqd->last_completed_rq_bfqq;
 		bfqq->tentative_waker_bfqq = NULL;
+		bfq_bfqq_name(bfqq->waker_bfqq, waker_name,
+			      MAX_BFQQ_NAME_LENGTH);
+		bfq_log_bfqq(bfqd, bfqq, "set waker %s", waker_name);
 
 		/*
 		 * If the waker queue disappears, then
-- 
2.26.2


  parent reply	other threads:[~2021-11-23 10:32 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-23 10:29 [PATCH 0/8 v4] bfq: Limit number of allocated scheduler tags per cgroup Jan Kara
2021-11-23 10:29 ` [PATCH 1/8] block: Provide icq in request allocation data Jan Kara
2021-11-23 16:06   ` Jens Axboe
2021-11-23 22:30     ` Jan Kara
2021-11-23 23:10       ` Jens Axboe
2021-11-23 10:29 ` [PATCH 2/8] bfq: Track number of allocated requests in bfq_entity Jan Kara
2021-11-23 10:29 ` [PATCH 3/8] bfq: Store full bitmap depth in bfq_data Jan Kara
2021-11-23 10:29 ` [PATCH 4/8] bfq: Limit number of requests consumed by each cgroup Jan Kara
2021-11-23 10:29 ` [PATCH 5/8] bfq: Limit waker detection in time Jan Kara
2021-11-23 10:29 ` [PATCH 6/8] bfq: Provide helper to generate bfqq name Jan Kara
2021-11-23 10:29 ` Jan Kara [this message]
2021-11-23 10:29 ` [PATCH 8/8] bfq: Do not let waker requests skip proper accounting Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2021-11-25 13:36 [PATCH 0/8 v5] bfq: Limit number of allocated scheduler tags per cgroup Jan Kara
2021-11-25 13:36 ` [PATCH 7/8] bfq: Log waker detections Jan Kara
2021-10-06 17:31 [PATCH 0/8 v3] bfq: Limit number of allocated scheduler tags per cgroup Jan Kara
2021-10-06 17:31 ` [PATCH 7/8] bfq: Log waker detections Jan Kara

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