[RFC PATCH 1/3] sched: add sched_policy and it's sysfs interface
From: Alex Shi
Date: Tue Nov 06 2012 - 08:12:38 EST
This patch add the power aware scheduler knob into sysfs:
$cat /sys/devices/system/cpu/sched_policy/available_sched_policy
performance powersaving
$cat /sys/devices/system/cpu/sched_policy/current_sched_policy
powersaving
The using sched policy is 'powersaving'. User can change the policy
by commend 'echo':
echo performance > /sys/devices/system/cpu/current_sched_policy
Power aware scheduling will has different behavior according to
different policy:
performance: the current scheduling behaviour, try to spread tasks
on more CPU sockets or cores.
powersaving: will shrink tasks into sched group until the group's
nr_running is up to group_weight.
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-devices-system-cpu | 21 +++++++
drivers/base/cpu.c | 2 +
include/linux/cpu.h | 2 +
kernel/sched/fair.c | 68 +++++++++++++++++++++-
kernel/sched/sched.h | 5 ++
5 files changed, 97 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 6943133..1909d3e 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -53,6 +53,27 @@ Description: Dynamic addition and removal of CPU's. This is not hotplug
the system. Information writtento the file to remove CPU's
is architecture specific.
+What: /sys/devices/system/cpu/sched_policy/current_sched_policy
+ /sys/devices/system/cpu/sched_policy/available_sched_policy
+Date: Oct 2012
+Contact: Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
+Description: CFS scheduler policy showing and setting interface.
+
+ available_sched_policy shows there are 2 kinds of policy now:
+ performance and powersaving.
+ current_sched_policy shows current scheduler policy. And user
+ can change the policy by writing it.
+
+ Policy decides that CFS scheduler how to distribute tasks onto
+ which CPU unit when tasks number less than LCPU number in system
+
+ performance: try to spread tasks onto more CPU sockets,
+ more CPU cores.
+
+ powersaving: try to shrink tasks onto same core or same CPU
+ until running task number beyond the LCPU number in the core
+ or socket.
+
What: /sys/devices/system/cpu/cpu#/node
Date: October 2009
Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx>
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 6345294..5f6a573 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -330,4 +330,6 @@ void __init cpu_dev_init(void)
panic("Failed to register CPU subsystem");
cpu_dev_register_generic();
+
+ create_sysfs_sched_policy_group(cpu_subsys.dev_root);
}
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ce7a074..b2e9265 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -36,6 +36,8 @@ extern void cpu_remove_dev_attr(struct device_attribute *attr);
extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
+extern int create_sysfs_sched_policy_group(struct device *dev);
+
#ifdef CONFIG_HOTPLUG_CPU
extern void unregister_cpu(struct cpu *cpu);
extern ssize_t arch_cpu_probe(const char *, size_t);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2cebc81..dedc576 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6383,7 +6383,6 @@ void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
#endif /* CONFIG_FAIR_GROUP_SCHED */
-
static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
{
struct sched_entity *se = &task->se;
@@ -6399,6 +6398,73 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
return rr_interval;
}
+/* The default scheduler policy is 'performance'. */
+int __read_mostly sched_policy = SCHED_POLICY_PERFORMANCE;
+
+#ifdef CONFIG_SYSFS
+static ssize_t show_available_sched_policy(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "performance powersaving\n");
+}
+
+static ssize_t show_current_sched_policy(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ if (sched_policy == SCHED_POLICY_PERFORMANCE)
+ return sprintf(buf, "performance\n");
+ else if (sched_policy == SCHED_POLICY_POWERSAVING)
+ return sprintf(buf, "powersaving\n");
+ return 0;
+}
+
+static ssize_t set_sched_policy(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ unsigned int ret = -EINVAL;
+ char str_policy[16];
+
+ ret = sscanf(buf, "%15s", str_policy);
+ if (ret != 1)
+ return -EINVAL;
+
+ if (!strcmp(str_policy, "performance"))
+ sched_policy = SCHED_POLICY_PERFORMANCE;
+ else if (!strcmp(str_policy, "powersaving"))
+ sched_policy = SCHED_POLICY_POWERSAVING;
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+/*
+ * * Sysfs setup bits:
+ * */
+static DEVICE_ATTR(current_sched_policy, 0644, show_current_sched_policy,
+ set_sched_policy);
+
+static DEVICE_ATTR(available_sched_policy, 0444,
+ show_available_sched_policy, NULL);
+
+static struct attribute *sched_policy_default_attrs[] = {
+ &dev_attr_current_sched_policy.attr,
+ &dev_attr_available_sched_policy.attr,
+ NULL
+};
+static struct attribute_group sched_policy_attr_group = {
+ .attrs = sched_policy_default_attrs,
+ .name = "sched_policy",
+};
+
+int __init create_sysfs_sched_policy_group(struct device *dev)
+{
+ return sysfs_create_group(&dev->kobj, &sched_policy_attr_group);
+}
+#endif /* CONFIG_SYSFS */
+
/*
* All the scheduling class methods:
*/
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 508e77e..9a6e06c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -9,6 +9,11 @@
extern __read_mostly int scheduler_running;
+#define SCHED_POLICY_PERFORMANCE (0x1)
+#define SCHED_POLICY_POWERSAVING (0x2)
+
+extern int __read_mostly sched_policy;
+
/*
* Convert user-nice values [ -20 ... 0 ... 19 ]
* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
--
1.7.12
--
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