Neil Horman 5ed963e5cb powerthresh: add hysteresis to powersave mode
We found that in some cases people were getting log spam from cpus constantly
leaving powersave mode.  This ensures that at least one cpu is in powersave mode
before we re-enable powersave on all cpus.

Signed-off-by: Neil Horman <>
2012-01-03 12:54:15 -05:00

218 lines
6 KiB

* Copyright (C) 2006, Intel Corporation
* This file is part of irqbalance
* This program file is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2 of the License.
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
* You should have received a copy of the GNU General Public License
* along with this program in a file named COPYING; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
* This file has the basic functions to manipulate interrupt metadata
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>
#include <math.h>
#include "types.h"
#include "irqbalance.h"
struct load_balance_info {
unsigned long long int total_load;
unsigned long long avg_load;
int load_sources;
unsigned long long int deviations;
long double std_deviation;
unsigned int num_within;
unsigned int num_over;
unsigned int num_under;
unsigned int num_powersave;
struct topo_obj *powersave;
static void gather_load_stats(struct topo_obj *obj, void *data)
struct load_balance_info *info = data;
info->total_load += obj->load;
info->load_sources += 1;
static void compute_deviations(struct topo_obj *obj, void *data)
struct load_balance_info *info = data;
unsigned long long int deviation;
deviation = (obj->load > info->avg_load) ?
obj->load - info->avg_load :
info->avg_load - obj->load;
info->deviations += (deviation * deviation);
static void move_candidate_irqs(struct irq_info *info, void *data)
int *remaining_deviation = (int *)data;
/* never move an irq that has an afinity hint when
* hint_policy is HINT_POLICY_EXACT
if (hint_policy == HINT_POLICY_EXACT)
if (!cpus_empty(info->affinity_hint))
/* Don't rebalance irqs that don't want it */
if (info->level == BALANCE_NONE)
/* Don't move cpus that only have one irq, regardless of load */
if (g_list_length(info->assigned_obj->interrupts) <= 1)
/* Stop rebalancing if we've estimated a full reduction of deviation */
if (*remaining_deviation <= 0)
*remaining_deviation -= info->load;
if (debug_mode)
printf("Selecting irq %d for rebalancing\n", info->irq);
migrate_irq(&info->assigned_obj->interrupts, &rebalance_irq_list, info);
info->assigned_obj = NULL;
static void migrate_overloaded_irqs(struct topo_obj *obj, void *data)
struct load_balance_info *info = data;
int deviation;
if (obj->powersave_mode)
* Don't rebalance irqs on objects whos load is below the average
if (obj->load <= info->avg_load) {
if ((obj->load + info->std_deviation) <= info->avg_load) {
if (!info->powersave)
if (!obj->powersave_mode)
info->powersave = obj;
} else
deviation = obj->load - info->avg_load;
if ((deviation > info->std_deviation) &&
(g_list_length(obj->interrupts) > 1)) {
* We have a cpu that is overloaded and
* has irqs that can be moved to fix that
/* order the list from least to greatest workload */
* Each irq carries a weighted average amount of load
* we think its responsible for. Set deviation to be the load
* of the difference between this objects load and the averate,
* and migrate irqs until we only have one left, or until that
* difference reaches zero
for_each_irq(obj->interrupts, move_candidate_irqs, &deviation);
} else
static void force_irq_migration(struct irq_info *info, void *data __attribute__((unused)))
migrate_irq(&info->assigned_obj->interrupts, &rebalance_irq_list, info);
static void clear_powersave_mode(struct topo_obj *obj, void *data __attribute__((unused)))
obj->powersave_mode = 0;
#define find_overloaded_objs(name, info) do {\
int ___load_sources;\
memset(&(info), 0, sizeof(struct load_balance_info));\
for_each_object((name), gather_load_stats, &(info));\
(info).avg_load = (info).total_load / (info).load_sources;\
for_each_object((name), compute_deviations, &(info));\
___load_sources = ((info).load_sources == 1) ? 1 : ((info).load_sources - 1);\
(info).std_deviation = (long double)((info).deviations / ___load_sources);\
(info).std_deviation = sqrt((info).std_deviation);\
for_each_object((name), migrate_overloaded_irqs, &(info));\
void update_migration_status(void)
struct load_balance_info info;
find_overloaded_objs(cpus, info);
if (cycle_count > 5) {
if (!info.num_over && (info.num_under >= power_thresh) && info.powersave) {
syslog(LOG_INFO, "cpu %d entering powersave mode\n", info.powersave->number);
info.powersave->powersave_mode = 1;
if (g_list_length(info.powersave->interrupts) > 0)
for_each_irq(info.powersave->interrupts, force_irq_migration, NULL);
} else if ((info.num_over) && (info.num_powersave)) {
syslog(LOG_INFO, "Load average increasing, re-enabling all cpus for irq balancing\n");
for_each_object(cpus, clear_powersave_mode, NULL);
find_overloaded_objs(cache_domains, info);
find_overloaded_objs(packages, info);
find_overloaded_objs(numa_nodes, info);
static void reset_irq_count(struct irq_info *info, void *unused __attribute__((unused)))
info->last_irq_count = info->irq_count;
info->irq_count = 0;
void reset_counts(void)
for_each_irq(NULL, reset_irq_count, NULL);
static void dump_workload(struct irq_info *info, void *unused __attribute__((unused)))
printf("Interrupt %i node_num %d (class %s) has workload %lu \n", info->irq, irq_numa_node(info)->number, classes[info->class], (unsigned long)info->load);
void dump_workloads(void)
for_each_irq(NULL, dump_workload, NULL);