Commit ea31f1c6 authored by Mete Durlu's avatar Mete Durlu Committed by Vasily Gorbik
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s390/hiperdispatch: Add hiperdispatch debug counters 



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: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarMete Durlu <meted@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 441cc6f5

arch/s390/kernel/hiperdispatch.c

+77 −0
Original line number Diff line number Diff line
@@ -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;

}