linux-kernel - [RFC PATCH 1/4] ksm: propose a auto-run mode of ksm

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Message-Id: <20220803100514.1653440-1-xu.xin16@zte.con.cn>
Date:   Wed,  3 Aug 2022 10:05:14 +0000
From:   cgel.zte@...il.com
To:     akpm@...ux-foundation.org
Cc:     hughd@...gle.com, izik.eidus@...ellosystems.com,
        willy@...radead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, xu xin <xu.xin16@....com.cn>,
        CGEL <cgel.zte@...il.com>
Subject: [RFC PATCH 1/4] ksm: propose a auto-run mode of ksm

From: xu xin <xu.xin16@....com.cn>

Add a new running state auto-mode to ksm. This is to pave the way
for subsequent real optimization features.

Use it by: echo 8 > /sys/kernel/mm/ksm/run

Signed-off-by: xu xin <xu.xin16@....com.cn>
Signed-off-by: CGEL <cgel.zte@...il.com>
---
 mm/ksm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 2f315c69fa2c..c80d908221a4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -290,6 +290,7 @@ static int ksm_nr_node_ids = 1;
 #define KSM_RUN_MERGE	1
 #define KSM_RUN_UNMERGE	2
 #define KSM_RUN_OFFLINE	4
+#define KSM_RUN_AUTO	8
 static unsigned long ksm_run = KSM_RUN_STOP;
 static void wait_while_offlining(void);
 
@@ -2416,7 +2417,9 @@ static void ksm_do_scan(unsigned int scan_npages)
 
 static int ksmd_should_run(void)
 {
-	return (ksm_run & KSM_RUN_MERGE) && !list_empty(&ksm_mm_head.mm_list);
+	if (!list_empty(&ksm_mm_head.mm_list))
+		return ksm_run & KSM_RUN_AUTO || ksm_run & KSM_RUN_MERGE;
+	return 0;
 }
 
 static int ksm_scan_thread(void *nothing)
@@ -2916,7 +2919,7 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
 	err = kstrtouint(buf, 10, &flags);
 	if (err)
 		return -EINVAL;
-	if (flags > KSM_RUN_UNMERGE)
+	if (flags > KSM_RUN_UNMERGE && flags != KSM_RUN_AUTO)
 		return -EINVAL;
 
 	/*
@@ -2942,7 +2945,7 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
 	}
 	mutex_unlock(&ksm_thread_mutex);
 
-	if (flags & KSM_RUN_MERGE)
+	if (flags & KSM_RUN_MERGE || flags & KSM_RUN_AUTO)
 		wake_up_interruptible(&ksm_thread_wait);
 
 	return count;
-- 
2.25.1