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/*
* Copyright (C) 2006, Intel Corporation
* Copyright (C) 2012, Neil Horman <nhorman@tuxdriver.com>
*
* 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;
unsigned long long min_load;
unsigned long long adjustment_load;
int load_sources;
unsigned long long int deviations;
long double std_deviation;
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;
if (info->load_sources == 0 || obj->load < info->min_load)
info->min_load = obj->load;
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)
{
struct load_balance_info *lb_info = data;
/* Don't rebalance irqs that don't want it */
if (info->level == BALANCE_NONE)
return;
/* Don't move cpus that only have one irq, regardless of load */
if (g_list_length(info->assigned_obj->interrupts) <= 1)
return;
/* IRQs with a load of 1 have most likely not had any interrupts and
* aren't worth migrating
*/
if (info->load <= 1)
return;
/* If we can migrate an irq without swapping the imbalance do it. */
if ((lb_info->adjustment_load - info->load) > (lb_info->min_load + info->load)) {
lb_info->adjustment_load -= info->load;
lb_info->min_load += info->load;
} else
return;
log(TO_CONSOLE, LOG_INFO, "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;
if (obj->powersave_mode)
info->num_powersave++;
if ((obj->load + info->std_deviation) <= info->avg_load) {
info->num_under++;
if (power_thresh != ULONG_MAX && !info->powersave)
if (!obj->powersave_mode)
info->powersave = obj;
} else if ((obj->load - info->std_deviation) >=info->avg_load) {
info->num_over++;
}
if ((obj->load > info->min_load) &&
(g_list_length(obj->interrupts) > 1)) {
/* order the list from greatest to least workload */
sort_irq_list(&obj->interrupts);
/*
* Each irq carries a weighted average amount of load
* we think it's responsible for. This object's load is larger
* than the object with the minimum load. Select irqs for
* migration if we could move them to the minimum object
* without reversing the imbalance or until we only have one
* left.
*/
info->adjustment_load = obj->load;
for_each_irq(obj->interrupts, move_candidate_irqs, info);
}
}
static void force_irq_migration(struct irq_info *info, void *data __attribute__((unused)))
{
migrate_irq(&info->assigned_obj->interrupts, &rebalance_irq_list, info);
info->assigned_obj = NULL;
}
static void clear_powersave_mode(struct topo_obj *obj, void *data __attribute__((unused)))
{
obj->powersave_mode = 0;
}
static void find_overloaded_objs(GList *name, struct load_balance_info *info) {
memset(info, 0, sizeof(struct load_balance_info));
for_each_object(name, gather_load_stats, info);
info->load_sources = (info->load_sources == 0) ? 1 : (info->load_sources);
info->avg_load = info->total_load / info->load_sources;
for_each_object(name, compute_deviations, info);
/* Don't divide by zero if there is a single load source */
if (info->load_sources == 1)
info->std_deviation = 0;
else {
info->std_deviation = (long double)(info->deviations / (info->load_sources - 1));
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 (power_thresh != ULONG_MAX && cycle_count > 5) {
if (!info.num_over && (info.num_under >= power_thresh) && info.powersave) {
log(TO_ALL, 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)) {
log(TO_ALL, 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 dump_workload(struct irq_info *info, void *unused __attribute__((unused)))
{
log(TO_CONSOLE, LOG_INFO, "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);
}