diff mbox series

[v4,2/4] mm/ksm: add sysfs knobs for advisor

Message ID 20231213182729.587081-3-shr@devkernel.io
State New
Headers
Series mm/ksm: Add ksm advisor |

Commit Message

Stefan Roesch Dec. 13, 2023, 6:27 p.m. UTC 
  This adds four new knobs for the KSM advisor to influence its behaviour.

The knobs are:
- advisor_mode:
    none:      no advisor (default)
    scan-time: scan time advisor
- advisor_max_cpu: 70 (default, cpu usage percent)
- advisor_min_pages_to_scan: 500 (default)
- advisor_max_pages_to_scan: 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@devkernel.io>
---
 mm/ksm.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 139 insertions(+), 3 deletions(-)

Comments

David Hildenbrand Dec. 18, 2023, 11:25 a.m. UTC | #1 
On 13.12.23 19:27, Stefan Roesch wrote:
> This adds four new knobs for the KSM advisor to influence its behaviour.
> 
> The knobs are:
> - advisor_mode:
>      none:      no advisor (default)
>      scan-time: scan time advisor
> - advisor_max_cpu: 70 (default, cpu usage percent)
> - advisor_min_pages_to_scan: 500 (default)
> - advisor_max_pages_to_scan: 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@devkernel.io>
> ---
>   mm/ksm.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 139 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 4f7b71a1f3112..f7387a6d02050 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -302,10 +302,10 @@ unsigned long ksm_zero_pages;
>   static unsigned long ksm_pages_skipped;
>   
>   /* Don't scan more than max pages per batch. */
> -static unsigned long ksm_advisor_max_pages = 30000;
> +static unsigned long ksm_advisor_max_pages_to_scan = 30000;
>   
>   /* At least scan this many pages per batch. */
> -static unsigned long ksm_advisor_min_pages = 500;
> +static unsigned long ksm_advisor_min_pages_to_scan = 500;
>   

That renaming should go into the previous patch.

>   /* Min CPU for scanning pages per scan */
>   static unsigned int ksm_advisor_min_cpu =  10;
> @@ -341,6 +341,16 @@ enum ksm_advisor_type {
>   };
>   static enum ksm_advisor_type ksm_advisor;
>   
> +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) {
> +		advisor_ctx = (const struct advisor_ctx){ 0 };
> +		ksm_thread_pages_to_scan = ksm_advisor_min_pages_to_scan;
> +	}
> +}
> +
>   static inline void advisor_start_scan(void)
>   {
>   	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
> @@ -434,7 +444,7 @@ static void scan_time_advisor(void)
>   
>   	pages = min(pages, per_page_cost * ksm_advisor_max_cpu);
>   	pages = max(pages, per_page_cost * ksm_advisor_min_cpu);
> -	pages = min(pages, ksm_advisor_max_pages);
> +	pages = min(pages, ksm_advisor_max_pages_to_scan);
>   
>   	/* Update advisor context */
>   	advisor_ctx.change = change;
> @@ -3722,6 +3732,127 @@ 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)
> +{
> +	const char *output;
> +
> +	if (ksm_advisor == KSM_ADVISOR_NONE)
> +		output = "[none] scan-time";
> +	else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
> +		output = "none [scan-time]";
> +
> +	return sysfs_emit(buf, "%s\n", output);
> +}
> +
> +static ssize_t advisor_mode_store(struct kobject *kobj,
> +				  struct kobj_attribute *attr, const char *buf,
> +				  size_t count)
> +{
> +	if (sysfs_streq("scan-time", buf))
> +		ksm_advisor = KSM_ADVISOR_SCAN_TIME;
> +	else if (sysfs_streq("none", buf))
> +		ksm_advisor = KSM_ADVISOR_NONE;
> +	else
> +		return -EINVAL;
> +
> +	/* Set advisor default values */
> +	set_advisor_defaults();

It probably makes sense to not reset the defaults if the ksm_advisor 
didn't change.

Apart form that, LGTM.
Stefan Roesch Dec. 18, 2023, 5:44 p.m. UTC | #2 
On Mon, Dec 18, 2023, at 3:25 AM, David Hildenbrand wrote:
> On 13.12.23 19:27, Stefan Roesch wrote:
>> This adds four new knobs for the KSM advisor to influence its behaviour.
>> 
>> The knobs are:
>> - advisor_mode:
>>      none:      no advisor (default)
>>      scan-time: scan time advisor
>> - advisor_max_cpu: 70 (default, cpu usage percent)
>> - advisor_min_pages_to_scan: 500 (default)
>> - advisor_max_pages_to_scan: 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@devkernel.io>
>> ---
>>   mm/ksm.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 139 insertions(+), 3 deletions(-)
>> 
>> diff --git a/mm/ksm.c b/mm/ksm.c
>> index 4f7b71a1f3112..f7387a6d02050 100644
>> --- a/mm/ksm.c
>> +++ b/mm/ksm.c
>> @@ -302,10 +302,10 @@ unsigned long ksm_zero_pages;
>>   static unsigned long ksm_pages_skipped;
>>   
>>   /* Don't scan more than max pages per batch. */
>> -static unsigned long ksm_advisor_max_pages = 30000;
>> +static unsigned long ksm_advisor_max_pages_to_scan = 30000;
>>   
>>   /* At least scan this many pages per batch. */
>> -static unsigned long ksm_advisor_min_pages = 500;
>> +static unsigned long ksm_advisor_min_pages_to_scan = 500;
>>   
>
> That renaming should go into the previous patch.
>

Moved it to the previous patch.

>>   /* Min CPU for scanning pages per scan */
>>   static unsigned int ksm_advisor_min_cpu =  10;
>> @@ -341,6 +341,16 @@ enum ksm_advisor_type {
>>   };
>>   static enum ksm_advisor_type ksm_advisor;
>>   
>> +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) {
>> +		advisor_ctx = (const struct advisor_ctx){ 0 };
>> +		ksm_thread_pages_to_scan = ksm_advisor_min_pages_to_scan;
>> +	}
>> +}
>> +
>>   static inline void advisor_start_scan(void)
>>   {
>>   	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
>> @@ -434,7 +444,7 @@ static void scan_time_advisor(void)
>>   
>>   	pages = min(pages, per_page_cost * ksm_advisor_max_cpu);
>>   	pages = max(pages, per_page_cost * ksm_advisor_min_cpu);
>> -	pages = min(pages, ksm_advisor_max_pages);
>> +	pages = min(pages, ksm_advisor_max_pages_to_scan);
>>   
>>   	/* Update advisor context */
>>   	advisor_ctx.change = change;
>> @@ -3722,6 +3732,127 @@ 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)
>> +{
>> +	const char *output;
>> +
>> +	if (ksm_advisor == KSM_ADVISOR_NONE)
>> +		output = "[none] scan-time";
>> +	else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
>> +		output = "none [scan-time]";
>> +
>> +	return sysfs_emit(buf, "%s\n", output);
>> +}
>> +
>> +static ssize_t advisor_mode_store(struct kobject *kobj,
>> +				  struct kobj_attribute *attr, const char *buf,
>> +				  size_t count)
>> +{
>> +	if (sysfs_streq("scan-time", buf))
>> +		ksm_advisor = KSM_ADVISOR_SCAN_TIME;
>> +	else if (sysfs_streq("none", buf))
>> +		ksm_advisor = KSM_ADVISOR_NONE;
>> +	else
>> +		return -EINVAL;
>> +
>> +	/* Set advisor default values */
>> +	set_advisor_defaults();
>
> It probably makes sense to not reset the defaults if the ksm_advisor 
> didn't change.
>

Added the above change.

> Apart form that, LGTM.
>
> -- 
> Cheers,
>
> David / dhildenb
diff mbox series

Patch

diff --git a/mm/ksm.c b/mm/ksm.c
index 4f7b71a1f3112..f7387a6d02050 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -302,10 +302,10 @@  unsigned long ksm_zero_pages;
 static unsigned long ksm_pages_skipped;
 
 /* Don't scan more than max pages per batch. */
-static unsigned long ksm_advisor_max_pages = 30000;
+static unsigned long ksm_advisor_max_pages_to_scan = 30000;
 
 /* At least scan this many pages per batch. */
-static unsigned long ksm_advisor_min_pages = 500;
+static unsigned long ksm_advisor_min_pages_to_scan = 500;
 
 /* Min CPU for scanning pages per scan */
 static unsigned int ksm_advisor_min_cpu =  10;
@@ -341,6 +341,16 @@  enum ksm_advisor_type {
 };
 static enum ksm_advisor_type ksm_advisor;
 
+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) {
+		advisor_ctx = (const struct advisor_ctx){ 0 };
+		ksm_thread_pages_to_scan = ksm_advisor_min_pages_to_scan;
+	}
+}
+
 static inline void advisor_start_scan(void)
 {
 	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
@@ -434,7 +444,7 @@  static void scan_time_advisor(void)
 
 	pages = min(pages, per_page_cost * ksm_advisor_max_cpu);
 	pages = max(pages, per_page_cost * ksm_advisor_min_cpu);
-	pages = min(pages, ksm_advisor_max_pages);
+	pages = min(pages, ksm_advisor_max_pages_to_scan);
 
 	/* Update advisor context */
 	advisor_ctx.change = change;
@@ -3722,6 +3732,127 @@  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)
+{
+	const char *output;
+
+	if (ksm_advisor == KSM_ADVISOR_NONE)
+		output = "[none] scan-time";
+	else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+		output = "none [scan-time]";
+
+	return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t advisor_mode_store(struct kobject *kobj,
+				  struct kobj_attribute *attr, const char *buf,
+				  size_t count)
+{
+	if (sysfs_streq("scan-time", buf))
+		ksm_advisor = KSM_ADVISOR_SCAN_TIME;
+	else if (sysfs_streq("none", buf))
+		ksm_advisor = KSM_ADVISOR_NONE;
+	else
+		return -EINVAL;
+
+	/* Set advisor default values */
+	set_advisor_defaults();
+
+	return count;
+}
+KSM_ATTR(advisor_mode);
+
+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_to_scan_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", ksm_advisor_min_pages_to_scan);
+}
+
+static ssize_t advisor_min_pages_to_scan_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_to_scan = value;
+	return count;
+}
+KSM_ATTR(advisor_min_pages_to_scan);
+
+static ssize_t advisor_max_pages_to_scan_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", ksm_advisor_max_pages_to_scan);
+}
+
+static ssize_t advisor_max_pages_to_scan_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_to_scan = value;
+	return count;
+}
+KSM_ATTR(advisor_max_pages_to_scan);
+
+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,
@@ -3744,6 +3875,11 @@  static struct attribute *ksm_attrs[] = {
 	&use_zero_pages_attr.attr,
 	&general_profit_attr.attr,
 	&smart_scan_attr.attr,
+	&advisor_mode_attr.attr,
+	&advisor_max_cpu_attr.attr,
+	&advisor_min_pages_to_scan_attr.attr,
+	&advisor_max_pages_to_scan_attr.attr,
+	&advisor_target_scan_time_attr.attr,
 	NULL,
 };