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From:   Kemeng Shi <shikemeng@huawei.com>
To:     <tj@kernel.org>, <josef@toxicpanda.com>, <axboe@kernel.dk>
CC:     <cgroups@vger.kernel.org>, <linux-block@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <shikemeng@huawei.com>
Subject: [PATCH v2 2/3] block: Correct comment for scale_cookie_change
Date:   Tue, 18 Oct 2022 19:12:39 +0800
Message-ID: <20221018111240.22612-3-shikemeng@huawei.com>
In-Reply-To: <20221018111240.22612-1-shikemeng@huawei.com>
References: <20221018111240.22612-1-shikemeng@huawei.com>
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Default queue depth of iolatency_grp is unlimited, so we scale down
quickly(once by half) in scale_cookie_change. Remove the "subtract
1/16th" part which is not the truth and add the actual way we
scale down.

Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
---
 block/blk-iolatency.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index b24d7b788ba3..2c574f98c8d1 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -364,9 +364,11 @@ static void scale_cookie_change(struct blk_iolatency *blkiolat,
 }
 
 /*
- * Change the queue depth of the iolatency_grp.  We add/subtract 1/16th of the
+ * Change the queue depth of the iolatency_grp.  We add 1/16th of the
  * queue depth at a time so we don't get wild swings and hopefully dial in to
- * fairer distribution of the overall queue depth.
+ * fairer distribution of the overall queue depth.  We halve the queue depth
+ * at a time so we can scale down queue depth quickly from default unlimited
+ * to target.
  */
 static void scale_change(struct iolatency_grp *iolat, bool up)
 {
-- 
2.30.0