[v3,2/4] mm/ksm: add sysfs knobs for advisor
Commit Message
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: 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@devkernel.io>
---
mm/ksm.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 127 insertions(+)
Comments
On 05.12.23 00:49, 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: 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@devkernel.io>
> ---
> mm/ksm.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 127 insertions(+)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index b27010fa2e946..18b7185bbc65b 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -3735,6 +3735,128 @@ 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 */
> + init_advisor();
Is the "init_advisor()" really required?
> + set_advisor_defaults();
That function should go to this patch.
On Tue, Dec 12, 2023, at 5:45 AM, David Hildenbrand wrote:
> On 05.12.23 00:49, 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: 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@devkernel.io>
>> ---
>> mm/ksm.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 127 insertions(+)
>>
>> diff --git a/mm/ksm.c b/mm/ksm.c
>> index b27010fa2e946..18b7185bbc65b 100644
>> --- a/mm/ksm.c
>> +++ b/mm/ksm.c
>> @@ -3735,6 +3735,128 @@ 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 */
>> + init_advisor();
>
> Is the "init_advisor()" really required?
>
The init_advisor is required for the following scenario:
- advisor is used
- advisor is turned off
- pages_to_scan is used and run for some time
- advisor is turned on again
==> Advisor would start with two high values for the first calculation
>> + set_advisor_defaults();
>
> That function should go to this patch.
>
>
>
I'll move it to this patch. I'll also look if I can should move init_advisor() to this
patch.
> --
> Cheers,
>
> David / dhildenb
On 12.12.23 19:02, Stefan Roesch wrote:
>
>
> On Tue, Dec 12, 2023, at 5:45 AM, David Hildenbrand wrote:
>> On 05.12.23 00:49, 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: 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@devkernel.io>
>>> ---
>>> mm/ksm.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 127 insertions(+)
>>>
>>> diff --git a/mm/ksm.c b/mm/ksm.c
>>> index b27010fa2e946..18b7185bbc65b 100644
>>> --- a/mm/ksm.c
>>> +++ b/mm/ksm.c
>>> @@ -3735,6 +3735,128 @@ 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 */
>>> + init_advisor();
>>
>> Is the "init_advisor()" really required?
>>
>
> The init_advisor is required for the following scenario:
> - advisor is used
> - advisor is turned off
> - pages_to_scan is used and run for some time
> - advisor is turned on again
> ==> Advisor would start with two high values for the first calculation
Can't set_advisor_defaults() handle that?
On Tue, Dec 12, 2023, at 10:07 AM, David Hildenbrand wrote:
> On 12.12.23 19:02, Stefan Roesch wrote:
>>
>>
>> On Tue, Dec 12, 2023, at 5:45 AM, David Hildenbrand wrote:
>>> On 05.12.23 00:49, 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: 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@devkernel.io>
>>>> ---
>>>> mm/ksm.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>> 1 file changed, 127 insertions(+)
>>>>
>>>> diff --git a/mm/ksm.c b/mm/ksm.c
>>>> index b27010fa2e946..18b7185bbc65b 100644
>>>> --- a/mm/ksm.c
>>>> +++ b/mm/ksm.c
>>>> @@ -3735,6 +3735,128 @@ 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 */
>>>> + init_advisor();
>>>
>>> Is the "init_advisor()" really required?
>>>
>>
>> The init_advisor is required for the following scenario:
>> - advisor is used
>> - advisor is turned off
>> - pages_to_scan is used and run for some time
>> - advisor is turned on again
>> ==> Advisor would start with two high values for the first calculation
>
> Can't set_advisor_defaults() handle that?
>
Yes, I can move the
advisor_ctx = (const struct advisor_ctx){ 0 };
into set_advisor_defaults().
> --
> Cheers,
>
> David / dhildenb
@@ -3735,6 +3735,128 @@ 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 */
+ init_advisor();
+ 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_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,
@@ -3757,6 +3879,11 @@ 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_attr.attr,
+ &advisor_max_pages_attr.attr,
+ &advisor_target_scan_time_attr.attr,
NULL,
};