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

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
Show 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 @@ small_imbalance:
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 @@ out_one_pinned:
(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