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s390/hiperdispatch: Add hiperdispatch debug counters

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Add three counters to follow and understand hiperdispatch behavior;
* adjustment_count (amount of capacity adjustments triggered)
* greedy_time_ms (time spent while all cpus are on high capacity)
* conservative_time_ms (time spent while only entitled cpus are on high
  capacity)

These counters can be found under /sys/kernel/debug/s390/hiperdispatch/
Time counters are in <msec> format and only cover the time spent
when hiperdispatch is active.

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 13:39:39 +02:00 committed by Vasily Gorbik
parent 441cc6f5b6
commit ea31f1c6b4
1 changed files with 77 additions and 0 deletions
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77
arch/s390/kernel/hiperdispatch.c
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@ -46,11 +46,13 @@
*/
#include <linux/cpumask.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/kernel_stat.h>
#include <linux/kstrtox.h>
#include <linux/ktime.h>
#include <linux/sysctl.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <asm/hiperdispatch.h>
#include <asm/setup.h>
@ -72,6 +74,9 @@ static int hd_entitled_cores; /* Total vertical high and medium CORE count */
static int hd_online_cores; /* Current online CORE count */
static unsigned long hd_previous_steal; /* Previous iteration's CPU steal timer total */
static unsigned long hd_high_time; /* Total time spent while all cpus have high capacity */
static unsigned long hd_low_time; /* Total time spent while vl cpus have low capacity */
static atomic64_t hd_adjustments; /* Total occurrence count of hiperdispatch adjustments */
static unsigned int hd_steal_threshold = HD_STEAL_THRESHOLD;
static unsigned int hd_delay_factor = HD_DELAY_FACTOR;
@ -121,6 +126,33 @@ void hd_add_core(int cpu)
}
}
/* Serialize update and read operations of debug counters. */
static DEFINE_MUTEX(hd_counter_mutex);
static void hd_update_times(void)
{
static ktime_t prev;
ktime_t now;
/*
* Check if hiperdispatch is active, if not set the prev to 0.
* This way it is possible to differentiate the first update iteration after
* enabling hiperdispatch.
*/
if (hd_entitled_cores == 0 || hd_enabled == 0) {
prev = ktime_set(0, 0);
return;
}
now = ktime_get();
if (ktime_after(prev, 0)) {
if (hd_high_capacity_cores == hd_online_cores)
hd_high_time += ktime_ms_delta(now, prev);
else
hd_low_time += ktime_ms_delta(now, prev);
}
prev = now;
}
static void hd_update_capacities(void)
{
int cpu, upscaling_cores;
@ -149,6 +181,9 @@ void hd_disable_hiperdispatch(void)
int hd_enable_hiperdispatch(void)
{
mutex_lock(&hd_counter_mutex);
hd_update_times();
mutex_unlock(&hd_counter_mutex);
if (hd_enabled == 0)
return 0;
if (hd_entitled_cores == 0)
@ -225,6 +260,7 @@ static void hd_capacity_work_fn(struct work_struct *work)
if (hd_high_capacity_cores != new_cores) {
trace_s390_hd_rebuild_domains(hd_high_capacity_cores, new_cores);
hd_high_capacity_cores = new_cores;
atomic64_inc(&hd_adjustments);
topology_schedule_update();
}
trace_s390_hd_work_fn(steal_percentage, hd_entitled_cores, hd_high_capacity_cores);
@ -327,6 +363,46 @@ static const struct attribute_group hd_attr_group = {
.attrs = hd_attrs,
};
static int hd_greedy_time_get(void *unused, u64 *val)
{
mutex_lock(&hd_counter_mutex);
hd_update_times();
*val = hd_high_time;
mutex_unlock(&hd_counter_mutex);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(hd_greedy_time_fops, hd_greedy_time_get, NULL, "%llu\n");
static int hd_conservative_time_get(void *unused, u64 *val)
{
mutex_lock(&hd_counter_mutex);
hd_update_times();
*val = hd_low_time;
mutex_unlock(&hd_counter_mutex);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(hd_conservative_time_fops, hd_conservative_time_get, NULL, "%llu\n");
static int hd_adjustment_count_get(void *unused, u64 *val)
{
*val = atomic64_read(&hd_adjustments);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(hd_adjustments_fops, hd_adjustment_count_get, NULL, "%llu\n");
static void __init hd_create_debugfs_counters(void)
{
struct dentry *dir;
dir = debugfs_create_dir("hiperdispatch", arch_debugfs_dir);
debugfs_create_file("conservative_time_ms", 0400, dir, NULL, &hd_conservative_time_fops);
debugfs_create_file("greedy_time_ms", 0400, dir, NULL, &hd_greedy_time_fops);
debugfs_create_file("adjustment_count", 0400, dir, NULL, &hd_adjustments_fops);
}
static void __init hd_create_attributes(void)
{
struct device *dev;
@ -347,6 +423,7 @@ 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_debugfs_counters();
hd_create_attributes();
return 0;
}