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s390/hiperdispatch: Add hiperdispatch debug attributes

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Add two attributes for debug purposes. They can be found under;
/sys/devices/system/cpu/hiperdispatch/
* hd_stime_threshold : allows user to adjust steal time threshold
* hd_delay_factor : allows user to adjust delay factor of hiperdispatch
                    work (after topology updates, delayed work is
                    always delayed extra by this factor)

hd_stime_threshold can have values between 0-100 as it represents a
percentage value.
hd_delay_factor can have values greater than 1. It is multiplied with
the default delay to achieve a longer interval, pushing back the next
hiperdispatch adjustment after a topology update.

Ex:
if delay interval is 250ms and the delay factor is 4;
delayed interval is now 1000ms(1sec). After each capacity adjustment
or topology change, work has a delayed interval of 1 sec for one
interval.

Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Mete Durlu 2024-08-12 13:39:38 +02:00 committed by Vasily Gorbik
parent b9271a5334
commit 441cc6f5b6
1 changed files with 82 additions and 2 deletions
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84
arch/s390/kernel/hiperdispatch.c
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@ -46,7 +46,9 @@
*/
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/kernel_stat.h>
#include <linux/kstrtox.h>
#include <linux/ktime.h>
#include <linux/sysctl.h>
#include <linux/workqueue.h>
@ -71,6 +73,8 @@ static int hd_online_cores; /* Current online CORE count */
static unsigned long hd_previous_steal; /* Previous iteration's CPU steal timer total */
static unsigned int hd_steal_threshold = HD_STEAL_THRESHOLD;
static unsigned int hd_delay_factor = HD_DELAY_FACTOR;
static int hd_enabled;
static void hd_capacity_work_fn(struct work_struct *work);
@ -151,7 +155,7 @@ int hd_enable_hiperdispatch(void)
return 0;
if (hd_online_cores <= hd_entitled_cores)
return 0;
mod_delayed_work(system_wq, &hd_capacity_work, HD_DELAY_INTERVAL * HD_DELAY_FACTOR);
mod_delayed_work(system_wq, &hd_capacity_work, HD_DELAY_INTERVAL * hd_delay_factor);
hd_update_capacities();
return 1;
}
@ -214,7 +218,7 @@ static void hd_capacity_work_fn(struct work_struct *work)
return;
}
steal_percentage = hd_steal_avg(hd_calculate_steal_percentage());
if (steal_percentage < HD_STEAL_THRESHOLD)
if (steal_percentage < hd_steal_threshold)
new_cores = hd_online_cores;
else
new_cores = hd_entitled_cores;
@ -260,6 +264,81 @@ static struct ctl_table hiperdispatch_ctl_table[] = {
},
};
static ssize_t hd_steal_threshold_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sysfs_emit(buf, "%u\n", hd_steal_threshold);
}
static ssize_t hd_steal_threshold_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned int val;
int rc;
rc = kstrtouint(buf, 0, &val);
if (rc)
return rc;
if (val > 100)
return -ERANGE;
hd_steal_threshold = val;
return count;
}
static DEVICE_ATTR_RW(hd_steal_threshold);
static ssize_t hd_delay_factor_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sysfs_emit(buf, "%u\n", hd_delay_factor);
}
static ssize_t hd_delay_factor_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned int val;
int rc;
rc = kstrtouint(buf, 0, &val);
if (rc)
return rc;
if (!val)
return -ERANGE;
hd_delay_factor = val;
return count;
}
static DEVICE_ATTR_RW(hd_delay_factor);
static struct attribute *hd_attrs[] = {
&dev_attr_hd_steal_threshold.attr,
&dev_attr_hd_delay_factor.attr,
NULL,
};
static const struct attribute_group hd_attr_group = {
.name = "hiperdispatch",
.attrs = hd_attrs,
};
static void __init hd_create_attributes(void)
{
struct device *dev;
dev = bus_get_dev_root(&cpu_subsys);
if (!dev)
return;
if (sysfs_create_group(&dev->kobj, &hd_attr_group))
pr_warn("Unable to create hiperdispatch attribute group\n");
put_device(dev);
}
static int __init hd_init(void)
{
if (IS_ENABLED(CONFIG_HIPERDISPATCH_ON)) {
@ -268,6 +347,7 @@ static int __init hd_init(void)
}
if (!register_sysctl("s390", hiperdispatch_ctl_table))
pr_warn("Failed to register s390.hiperdispatch sysctl attribute\n");
hd_create_attributes();
return 0;
}
late_initcall(hd_init);