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Message-Id: <20231028000945.2428830-3-shr@devkernel.io>
Date: Fri, 27 Oct 2023 17:09:43 -0700
From: Stefan Roesch <shr@...kernel.io>
To: kernel-team@...com
Cc: shr@...kernel.io, akpm@...ux-foundation.org, david@...hat.com,
hannes@...xchg.org, riel@...riel.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: [PATCH v2 2/4] mm/ksm: add sysfs knobs for advisor
This adds four new knobs for the KSM advisor to influence its behaviour.
The knobs are:
- advisor_mode:
0: no advisor (default)
1: scan time advisor
- advisor_min_cpu: 15 (default, cpu usage percent)
- advisor_max_cpu: 70 (default, cpu usage percent)
- advisor_min_pages: 500 (default)
- advisor_max_pages: 30000 (default)
- advisor_target_scan_time: 200 (default in seconds)
The new values will take effect on the next scan round.
Signed-off-by: Stefan Roesch <shr@...kernel.io>
---
mm/ksm.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 154 insertions(+)
diff --git a/mm/ksm.c b/mm/ksm.c
index e18fecfb359d..042ecaeb0beb 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -351,6 +351,14 @@ static void init_advisor(void)
advisor_ctx.cpu_time = 0;
}
+static void set_advisor_defaults(void)
+{
+ if (ksm_advisor == KSM_ADVISOR_NONE)
+ ksm_thread_pages_to_scan = DEFAULT_PAGES_TO_SCAN;
+ else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+ ksm_thread_pages_to_scan = ksm_advisor_min_pages;
+}
+
/*
* Use previous scan time if available, otherwise use current scan time as an
* approximation for the previous scan time.
@@ -3719,6 +3727,146 @@ static ssize_t smart_scan_store(struct kobject *kobj,
}
KSM_ATTR(smart_scan);
+static ssize_t advisor_mode_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", ksm_advisor);
+}
+
+static ssize_t advisor_mode_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf,
+ size_t count)
+{
+ unsigned int mode;
+ int err;
+
+ err = kstrtouint(buf, 10, &mode);
+ if (err)
+ return -EINVAL;
+ if (mode > KSM_ADVISOR_LAST)
+ return -EINVAL;
+
+ /* Set advisor default values */
+ ksm_advisor = mode;
+ init_advisor();
+ set_advisor_defaults();
+
+ return count;
+}
+KSM_ATTR(advisor_mode);
+
+static ssize_t advisor_min_cpu_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", ksm_advisor_min_cpu);
+}
+
+static ssize_t advisor_min_cpu_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long value;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return -EINVAL;
+
+ ksm_advisor_min_cpu = value;
+ return count;
+}
+KSM_ATTR(advisor_min_cpu);
+
+static ssize_t advisor_max_cpu_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", ksm_advisor_max_cpu);
+}
+
+static ssize_t advisor_max_cpu_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long value;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return -EINVAL;
+
+ ksm_advisor_max_cpu = value;
+ return count;
+}
+KSM_ATTR(advisor_max_cpu);
+
+static ssize_t advisor_min_pages_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%lu\n", ksm_advisor_min_pages);
+}
+
+static ssize_t advisor_min_pages_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long value;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return -EINVAL;
+
+ ksm_advisor_min_pages = value;
+ return count;
+}
+KSM_ATTR(advisor_min_pages);
+
+static ssize_t advisor_max_pages_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%lu\n", ksm_advisor_max_pages);
+}
+
+static ssize_t advisor_max_pages_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long value;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return -EINVAL;
+
+ ksm_advisor_max_pages = value;
+ return count;
+}
+KSM_ATTR(advisor_max_pages);
+
+static ssize_t advisor_target_scan_time_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%lu\n", ksm_advisor_target_scan_time);
+}
+
+static ssize_t advisor_target_scan_time_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long value;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return -EINVAL;
+ if (value < 1)
+ return -EINVAL;
+
+ ksm_advisor_target_scan_time = value;
+ return count;
+}
+KSM_ATTR(advisor_target_scan_time);
+
static struct attribute *ksm_attrs[] = {
&sleep_millisecs_attr.attr,
&pages_to_scan_attr.attr,
@@ -3741,6 +3889,12 @@ static struct attribute *ksm_attrs[] = {
&use_zero_pages_attr.attr,
&general_profit_attr.attr,
&smart_scan_attr.attr,
+ &advisor_mode_attr.attr,
+ &advisor_min_cpu_attr.attr,
+ &advisor_max_cpu_attr.attr,
+ &advisor_min_pages_attr.attr,
+ &advisor_max_pages_attr.attr,
+ &advisor_target_scan_time_attr.attr,
NULL,
};
--
2.39.3
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