[PATCH 2/2] mm/compaction: expose a new param for proactive compaction

[Michal Clapinski <mclapinski@xxxxxxxxxx>]

Expose the diff between low and high watermark as a sysctl var.

Signed-off-by: Michal Clapinski <mclapinski@xxxxxxxxxx>
---
 mm/compaction.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 29524242a16ef..fd546b797e544 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1921,6 +1921,7 @@ static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNE
  * background. It takes values in the range [0, 100].
  */
 static unsigned int __read_mostly sysctl_compaction_proactiveness = 20;
+static unsigned int __read_mostly sysctl_compaction_proactiveness_leeway = 10;
 static int sysctl_extfrag_threshold = 500;
 static int __read_mostly sysctl_compact_memory;
 
@@ -2254,7 +2255,7 @@ static unsigned int fragmentation_score_wmark(bool low)
 	 * close to 100 (maximum).
 	 */
 	wmark_low = 100U - sysctl_compaction_proactiveness;
-	return low ? wmark_low : min(wmark_low + 10, 100U);
+	return low ? wmark_low : min(wmark_low + sysctl_compaction_proactiveness_leeway, 100U);
 }
 
 static bool should_proactive_compact_node(pg_data_t *pgdat)
@@ -3314,6 +3315,15 @@ static struct ctl_table vm_compaction[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE_HUNDRED,
 	},
+	{
+		.procname	= "compaction_proactiveness_leeway",
+		.data		= &sysctl_compaction_proactiveness_leeway,
+		.maxlen		= sizeof(sysctl_compaction_proactiveness_leeway),
+		.mode		= 0644,
+		.proc_handler	= compaction_proactiveness_sysctl_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE_HUNDRED,
+	},
 	{
 		.procname	= "extfrag_threshold",
 		.data		= &sysctl_extfrag_threshold,
-- 
2.48.1.262.g85cc9f2d1e-goog