linux-kernel - [PATCH v2 1/2] mm/compaction: remove low watermark cap for proactive compaction

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Message-ID: <20250127214627.4021412-2-mclapinski@google.com>
Date: Mon, 27 Jan 2025 22:46:26 +0100
From: Michal Clapinski <mclapinski@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>, 
	Pasha Tatashin <tatashin@...gle.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Michal Clapinski <mclapinski@...gle.com>
Subject: [PATCH v2 1/2] mm/compaction: remove low watermark cap for proactive compaction

Previously a min cap of 5 has been set in the commit introducing
proactive compaction. This was to make sure users don't hurt themselves
by setting the proactiveness to 100 and making their system
unresponsive. But the compaction mechanism has a backoff mechanism that
will sleep for 30s if no progress is made, so I don't see a significant
risk here. My system (20GB of memory) has been perfectly fine with
proactiveness set to 100 and leeway set to 0.

Signed-off-by: Michal Clapinski <mclapinski@...gle.com>
Change-Id: I007e3a02d126d3858ceecf5ce57a1c360177c37b
---
 mm/compaction.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index a2b16b08cbbff..29524242a16ef 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2253,7 +2253,7 @@ static unsigned int fragmentation_score_wmark(bool low)
 	 * activity in case a user sets the proactiveness tunable
 	 * close to 100 (maximum).
 	 */
-	wmark_low = max(100U - sysctl_compaction_proactiveness, 5U);
+	wmark_low = 100U - sysctl_compaction_proactiveness;
 	return low ? wmark_low : min(wmark_low + 10, 100U);
 }
 
-- 
2.48.1.262.g85cc9f2d1e-goog