linux-kernel - [PATCH 3/4] block, bfq: increase update frequency of inject limit

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Message-Id: <20190822152037.15413-4-paolo.valente@linaro.org>
Date:   Thu, 22 Aug 2019 17:20:36 +0200
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        ulf.hansson@...aro.org, linus.walleij@...aro.org,
        bfq-iosched@...glegroups.com, oleksandr@...alenko.name,
        Paolo Valente <paolo.valente@...aro.org>
Subject: [PATCH 3/4] block, bfq: increase update frequency of inject limit

The update period of the injection limit has been tentatively set to
100 ms, to reduce fluctuations. This value however proved to cause,
occasionally, the limit to be decremented for some bfq_queue only
after the queue underwent excessive injection for a lot of time. This
commit reduces the period to 10 ms.

Signed-off-by: Paolo Valente <paolo.valente@...aro.org>
---
 block/bfq-iosched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index e114282204f6..ddac93e910fa 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2016,7 +2016,7 @@ static void bfq_add_request(struct request *rq)
 		     (bfqq->last_serv_time_ns > 0 &&
 		      bfqd->rqs_injected && bfqd->rq_in_driver > 0)) &&
 		    time_is_before_eq_jiffies(bfqq->decrease_time_jif +
-					      msecs_to_jiffies(100))) {
+					      msecs_to_jiffies(10))) {
 			bfqd->last_empty_occupied_ns = ktime_get_ns();
 			/*
 			 * Start the state machine for measuring the
-- 
2.20.1