linux-kernel - [PATCH 01/11] mm/damon/core: Use better timer mechanisms selection threshold

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Message-Id: <20211201150440.1088-2-sj@kernel.org>
Date:   Wed,  1 Dec 2021 15:04:30 +0000
From:   SeongJae Park <sj@...nel.org>
To:     akpm@...ux-foundation.org
Cc:     shuah@...nel.org, brendanhiggins@...gle.com, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        SeongJae Park <sj@...nel.org>
Subject: [PATCH 01/11] mm/damon/core: Use better timer mechanisms selection threshold

DAMON is using hrtimer if requested sleep time is <=100ms, while the
suggested threshold[1] is <=20ms.  This commit applies the threshold.

[1] Documentation/timers/timers-howto.rst

Fixes: ee801b7dd7822 ("mm/damon/schemes: activate schemes based on a watermarks mechanism")
Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 8cd8fddc931e..ccc62479549a 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -978,7 +978,8 @@ static unsigned long damos_wmark_wait_us(struct damos *scheme)
 
 static void kdamond_usleep(unsigned long usecs)
 {
-	if (usecs > 100 * 1000)
+	/* See Documentation/timers/timers-howto.rst for the thresholds */
+	if (usecs > 20 * USEC_PER_MSEC)
 		schedule_timeout_idle(usecs_to_jiffies(usecs));
 	else
 		usleep_idle_range(usecs, usecs + 1);
-- 
2.17.1