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[PATCH] sched: mc/smt power savings sched policy

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sysfs entries 'sched_mc_power_savings' and 'sched_smt_power_savings' in
/sys/devices/system/cpu/ control the MC/SMT power savings policy for the
scheduler.

Based on the values (1-enable, 0-disable) for these controls, sched groups
cpu power will be determined for different domains.  When power savings
policy is enabled and under light load conditions, scheduler will minimize
the physical packages/cpu cores carrying the load and thus conserving
power(with a perf impact based on the workload characteristics...  see OLS
2005 CMP kernel scheduler paper for more details..)

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Con Kolivas <kernel@kolivas.org>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Siddha, Suresh B 2006-06-27 02:54:42 -07:00 committed by Linus Torvalds
parent 369381694d
commit 5c45bf279d
11 changed files with 264 additions and 35 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

8
arch/i386/kernel/smpboot.c
View file

@ -448,10 +448,12 @@ cpumask_t cpu_coregroup_map(int cpu)
struct cpuinfo_x86 *c = cpu_data + cpu;
/*
* For perf, we return last level cache shared map.
* TBD: when power saving sched policy is added, we will return
* cpu_core_map when power saving policy is enabled
* And for power savings, we return cpu_core_map
*/
return c->llc_shared_map;
if (sched_mc_power_savings || sched_smt_power_savings)
return cpu_core_map[cpu];
else
return c->llc_shared_map;
}
/* representing cpus for which sibling maps can be computed */

8
arch/x86_64/kernel/smpboot.c
View file

@ -455,10 +455,12 @@ cpumask_t cpu_coregroup_map(int cpu)
struct cpuinfo_x86 *c = cpu_data + cpu;
/*
* For perf, we return last level cache shared map.
* TBD: when power saving sched policy is added, we will return
* cpu_core_map when power saving policy is enabled
* And for power savings, we return cpu_core_map
*/
return c->llc_shared_map;
if (sched_mc_power_savings || sched_smt_power_savings)
return cpu_core_map[cpu];
else
return c->llc_shared_map;
}
/* representing cpus for which sibling maps can be computed */

10
drivers/base/cpu.c
View file

@ -143,5 +143,13 @@ EXPORT_SYMBOL_GPL(get_cpu_sysdev);
int __init cpu_dev_init(void)
{
return sysdev_class_register(&cpu_sysdev_class);
int err;
err = sysdev_class_register(&cpu_sysdev_class);
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
if (!err)
err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
#endif
return err;
}

5
include/asm-i386/topology.h
View file

@ -112,4 +112,9 @@ extern unsigned long node_remap_size[];
extern cpumask_t cpu_coregroup_map(int cpu);
#ifdef CONFIG_SMP
#define mc_capable() (boot_cpu_data.x86_max_cores > 1)
#define smt_capable() (smp_num_siblings > 1)
#endif
#endif /* _ASM_I386_TOPOLOGY_H */

1
include/asm-ia64/topology.h
View file

@ -112,6 +112,7 @@ void build_cpu_to_node_map(void);
#define topology_core_id(cpu) (cpu_data(cpu)->core_id)
#define topology_core_siblings(cpu) (cpu_core_map[cpu])
#define topology_thread_siblings(cpu) (cpu_sibling_map[cpu])
#define smt_capable() (smp_num_siblings > 1)
#endif
#include <asm-generic/topology.h>

5
include/asm-powerpc/topology.h
View file

@ -93,5 +93,10 @@ static inline void sysfs_remove_device_from_node(struct sys_device *dev,
#endif /* CONFIG_NUMA */
#ifdef CONFIG_SMP
#include <asm/cputable.h>
#define smt_capable() (cpu_has_feature(CPU_FTR_SMT))
#endif
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_TOPOLOGY_H */

3
include/asm-sparc64/topology.h
View file

@ -1,6 +1,9 @@
#ifndef _ASM_SPARC64_TOPOLOGY_H
#define _ASM_SPARC64_TOPOLOGY_H
#include <asm/spitfire.h>
#define smt_capable() (tlb_type == hypervisor)
#include <asm-generic/topology.h>
#endif /* _ASM_SPARC64_TOPOLOGY_H */

2
include/asm-x86_64/topology.h
View file

@ -59,6 +59,8 @@ extern int __node_distance(int, int);
#define topology_core_id(cpu) (cpu_data[cpu].cpu_core_id)
#define topology_core_siblings(cpu) (cpu_core_map[cpu])
#define topology_thread_siblings(cpu) (cpu_sibling_map[cpu])
#define mc_capable() (boot_cpu_data.x86_max_cores > 1)
#define smt_capable() (smp_num_siblings > 1)
#endif
#include <asm-generic/topology.h>

10
include/linux/sched.h
View file

@ -570,6 +570,11 @@ enum idle_type
#define SD_WAKE_AFFINE 32 /* Wake task to waking CPU */
#define SD_WAKE_BALANCE 64 /* Perform balancing at task wakeup */
#define SD_SHARE_CPUPOWER 128 /* Domain members share cpu power */
#define SD_POWERSAVINGS_BALANCE 256 /* Balance for power savings */
#define BALANCE_FOR_POWER ((sched_mc_power_savings || sched_smt_power_savings) \
? SD_POWERSAVINGS_BALANCE : 0)
struct sched_group {
struct sched_group *next; /* Must be a circular list */
@ -1412,6 +1417,11 @@ static inline void arch_pick_mmap_layout(struct mm_struct *mm)
extern long sched_setaffinity(pid_t pid, cpumask_t new_mask);
extern long sched_getaffinity(pid_t pid, cpumask_t *mask);
#include <linux/sysdev.h>
extern int sched_mc_power_savings, sched_smt_power_savings;
extern struct sysdev_attribute attr_sched_mc_power_savings, attr_sched_smt_power_savings;
extern int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls);
extern void normalize_rt_tasks(void);
#ifdef CONFIG_PM

3
include/linux/topology.h
View file

@ -134,7 +134,8 @@
.flags = SD_LOAD_BALANCE \
| SD_BALANCE_NEWIDLE \
| SD_BALANCE_EXEC \
| SD_WAKE_AFFINE, \
| SD_WAKE_AFFINE \
| BALANCE_FOR_POWER, \
.last_balance = jiffies, \
.balance_interval = 1, \
.nr_balance_failed = 0, \

244
kernel/sched.c
View file

@ -1162,6 +1162,11 @@ static int sched_balance_self(int cpu, int flag)
struct sched_domain *tmp, *sd = NULL;
for_each_domain(cpu, tmp) {
/*
* If power savings logic is enabled for a domain, stop there.
*/
if (tmp->flags & SD_POWERSAVINGS_BALANCE)
break;
if (tmp->flags & flag)
sd = tmp;
}
@ -2082,6 +2087,12 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
unsigned long busiest_load_per_task, busiest_nr_running;
unsigned long this_load_per_task, this_nr_running;
int load_idx;
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
int power_savings_balance = 1;
unsigned long leader_nr_running = 0, min_load_per_task = 0;
unsigned long min_nr_running = ULONG_MAX;
struct sched_group *group_min = NULL, *group_leader = NULL;
#endif
max_load = this_load = total_load = total_pwr = 0;
busiest_load_per_task = busiest_nr_running = 0;
@ -2094,7 +2105,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
load_idx = sd->idle_idx;
do {
unsigned long load;
unsigned long load, group_capacity;
int local_group;
int i;
unsigned long sum_nr_running, sum_weighted_load;
@ -2127,18 +2138,76 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
/* Adjust by relative CPU power of the group */
avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
group_capacity = group->cpu_power / SCHED_LOAD_SCALE;
if (local_group) {
this_load = avg_load;
this = group;
this_nr_running = sum_nr_running;
this_load_per_task = sum_weighted_load;
} else if (avg_load > max_load &&
sum_nr_running > group->cpu_power / SCHED_LOAD_SCALE) {
sum_nr_running > group_capacity) {
max_load = avg_load;
busiest = group;
busiest_nr_running = sum_nr_running;
busiest_load_per_task = sum_weighted_load;
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/*
* Busy processors will not participate in power savings
* balance.
*/
if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
goto group_next;
/*
* If the local group is idle or completely loaded
* no need to do power savings balance at this domain
*/
if (local_group && (this_nr_running >= group_capacity ||
!this_nr_running))
power_savings_balance = 0;
/*
* If a group is already running at full capacity or idle,
* don't include that group in power savings calculations
*/
if (!power_savings_balance || sum_nr_running >= group_capacity
|| !sum_nr_running)
goto group_next;
/*
* Calculate the group which has the least non-idle load.
* This is the group from where we need to pick up the load
* for saving power
*/
if ((sum_nr_running < min_nr_running) ||
(sum_nr_running == min_nr_running &&
first_cpu(group->cpumask) <
first_cpu(group_min->cpumask))) {
group_min = group;
min_nr_running = sum_nr_running;
min_load_per_task = sum_weighted_load /
sum_nr_running;
}
/*
* Calculate the group which is almost near its
* capacity but still has some space to pick up some load
* from other group and save more power
*/
if (sum_nr_running <= group_capacity - 1)
if (sum_nr_running > leader_nr_running ||
(sum_nr_running == leader_nr_running &&
first_cpu(group->cpumask) >
first_cpu(group_leader->cpumask))) {
group_leader = group;
leader_nr_running = sum_nr_running;
}
group_next:
#endif
group = group->next;
} while (group != sd->groups);
@ -2247,7 +2316,16 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
return busiest;
out_balanced:
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
goto ret;
if (this == group_leader && group_leader != group_min) {
*imbalance = min_load_per_task;
return group_min;
}
ret:
#endif
*imbalance = 0;
return NULL;
}
@ -2300,7 +2378,8 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
int active_balance = 0;
int sd_idle = 0;
if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER)
if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
!sched_smt_power_savings)
sd_idle = 1;
schedstat_inc(sd, lb_cnt[idle]);
@ -2389,7 +2468,8 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
sd->balance_interval *= 2;
}
if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER)
if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!sched_smt_power_savings)
return -1;
return nr_moved;
@ -2404,7 +2484,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
(sd->balance_interval < sd->max_interval))
sd->balance_interval *= 2;
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER)
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && !sched_smt_power_savings)
return -1;
return 0;
}
@ -2425,7 +2505,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
int nr_moved = 0;
int sd_idle = 0;
if (sd->flags & SD_SHARE_CPUPOWER)
if (sd->flags & SD_SHARE_CPUPOWER && !sched_smt_power_savings)
sd_idle = 1;
schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
@ -2466,7 +2546,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
out_balanced:
schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER)
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && !sched_smt_power_savings)
return -1;
sd->nr_balance_failed = 0;
return 0;
@ -5732,6 +5812,7 @@ static cpumask_t sched_domain_node_span(int node)
}
#endif
int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
/*
* At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
* can switch it on easily if needed.
@ -6113,37 +6194,72 @@ static int build_sched_domains(const cpumask_t *cpu_map)
#endif
/* Calculate CPU power for physical packages and nodes */
#ifdef CONFIG_SCHED_SMT
for_each_cpu_mask(i, *cpu_map) {
struct sched_domain *sd;
sd = &per_cpu(cpu_domains, i);
sd->groups->cpu_power = SCHED_LOAD_SCALE;
}
#endif
#ifdef CONFIG_SCHED_MC
for_each_cpu_mask(i, *cpu_map) {
int power;
struct sched_domain *sd;
#ifdef CONFIG_SCHED_SMT
sd = &per_cpu(cpu_domains, i);
power = SCHED_LOAD_SCALE;
sd->groups->cpu_power = power;
#endif
#ifdef CONFIG_SCHED_MC
sd = &per_cpu(core_domains, i);
power = SCHED_LOAD_SCALE + (cpus_weight(sd->groups->cpumask)-1)
if (sched_smt_power_savings)
power = SCHED_LOAD_SCALE * cpus_weight(sd->groups->cpumask);
else
power = SCHED_LOAD_SCALE + (cpus_weight(sd->groups->cpumask)-1)
* SCHED_LOAD_SCALE / 10;
sd->groups->cpu_power = power;
}
#endif
for_each_cpu_mask(i, *cpu_map) {
struct sched_domain *sd;
#ifdef CONFIG_SCHED_MC
sd = &per_cpu(phys_domains, i);
if (i != first_cpu(sd->groups->cpumask))
continue;
/*
* This has to be < 2 * SCHED_LOAD_SCALE
* Lets keep it SCHED_LOAD_SCALE, so that
* while calculating NUMA group's cpu_power
* we can simply do
* numa_group->cpu_power += phys_group->cpu_power;
*
* See "only add power once for each physical pkg"
* comment below
*/
sd->groups->cpu_power = SCHED_LOAD_SCALE;
sd->groups->cpu_power = 0;
if (sched_mc_power_savings || sched_smt_power_savings) {
int j;
for_each_cpu_mask(j, sd->groups->cpumask) {
struct sched_domain *sd1;
sd1 = &per_cpu(core_domains, j);
/*
* for each core we will add once
* to the group in physical domain
*/
if (j != first_cpu(sd1->groups->cpumask))
continue;
if (sched_smt_power_savings)
sd->groups->cpu_power += sd1->groups->cpu_power;
else
sd->groups->cpu_power += SCHED_LOAD_SCALE;
}
} else
/*
* This has to be < 2 * SCHED_LOAD_SCALE
* Lets keep it SCHED_LOAD_SCALE, so that
* while calculating NUMA group's cpu_power
* we can simply do
* numa_group->cpu_power += phys_group->cpu_power;
*
* See "only add power once for each physical pkg"
* comment below
*/
sd->groups->cpu_power = SCHED_LOAD_SCALE;
#else
int power;
sd = &per_cpu(phys_domains, i);
power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
(cpus_weight(sd->groups->cpumask)-1) / 10;
if (sched_smt_power_savings)
power = SCHED_LOAD_SCALE * cpus_weight(sd->groups->cpumask);
else
power = SCHED_LOAD_SCALE;
sd->groups->cpu_power = power;
#endif
}
@ -6244,6 +6360,80 @@ int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
return err;
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
int arch_reinit_sched_domains(void)
{
int err;
lock_cpu_hotplug();
detach_destroy_domains(&cpu_online_map);
err = arch_init_sched_domains(&cpu_online_map);
unlock_cpu_hotplug();
return err;
}
static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
{
int ret;
if (buf[0] != '0' && buf[0] != '1')
return -EINVAL;
if (smt)
sched_smt_power_savings = (buf[0] == '1');
else
sched_mc_power_savings = (buf[0] == '1');
ret = arch_reinit_sched_domains();
return ret ? ret : count;
}
int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
{
int err = 0;
#ifdef CONFIG_SCHED_SMT
if (smt_capable())
err = sysfs_create_file(&cls->kset.kobj,
&attr_sched_smt_power_savings.attr);
#endif
#ifdef CONFIG_SCHED_MC
if (!err && mc_capable())
err = sysfs_create_file(&cls->kset.kobj,
&attr_sched_mc_power_savings.attr);
#endif
return err;
}
#endif
#ifdef CONFIG_SCHED_MC
static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
{
return sprintf(page, "%u\n", sched_mc_power_savings);
}
static ssize_t sched_mc_power_savings_store(struct sys_device *dev, const char *buf, size_t count)
{
return sched_power_savings_store(buf, count, 0);
}
SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
sched_mc_power_savings_store);
#endif
#ifdef CONFIG_SCHED_SMT
static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
{
return sprintf(page, "%u\n", sched_smt_power_savings);
}
static ssize_t sched_smt_power_savings_store(struct sys_device *dev, const char *buf, size_t count)
{
return sched_power_savings_store(buf, count, 1);
}
SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
sched_smt_power_savings_store);
#endif
#ifdef CONFIG_HOTPLUG_CPU
/*
* Force a reinitialization of the sched domains hierarchy. The domains