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SubjectRe: [PATCH v3 14/22] sched: add sched_policy and it's sysfs interface
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Hi Alex,

Just a few nitpickings..


On Sat, 5 Jan 2013 16:37:43 +0800, Alex Shi wrote:
> This patch add the power aware scheduler knob into sysfs:
>
> $cat /sys/devices/system/cpu/sched_policy/available_sched_policy
> performance powersaving balance
> $cat /sys/devices/system/cpu/sched_policy/current_sched_policy
> powersaving
>
> This means the using sched policy is 'powersaving'.
>
> User can change the policy by commend 'echo':
> echo performance > /sys/devices/system/cpu/current_sched_policy
>
> Signed-off-by: Alex Shi <alex.shi@intel.com>
> ---
> Documentation/ABI/testing/sysfs-devices-system-cpu | 24 +++++++
> kernel/sched/fair.c | 76 ++++++++++++++++++++++
> 2 files changed, 100 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
> index 6943133..9c9acbf 100644
> --- a/Documentation/ABI/testing/sysfs-devices-system-cpu
> +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
> @@ -53,6 +53,30 @@ 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@vger.kernel.org>
> +Description: CFS scheduler policy showing and setting interface.
> +
> + available_sched_policy shows there are 3 kinds of policy now:
> + performance, balance 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 every LCPUs are busy.
> +
> + balance: try to shrink tasks onto same core or same CPU
> + until full powered CPUs are busy. This policy also consider
> + system performance when try to save power.
> +
> What: /sys/devices/system/cpu/cpu#/node
> Date: October 2009
> Contact: Linux memory management mailing list <linux-mm@kvack.org>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index f24aca6..ee015b8 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6102,6 +6102,82 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
>
> /* 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)

This line can be combined to the above line.


> +{
> + return sprintf(buf, "performance balance powersaving\n");
> +}
> +
> +static ssize_t show_current_sched_policy(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)

Ditto.


> +{
> + if (sched_policy == SCHED_POLICY_PERFORMANCE)
> + return sprintf(buf, "performance\n");
> + else if (sched_policy == SCHED_POLICY_POWERSAVING)
> + return sprintf(buf, "powersaving\n");
> + else if (sched_policy == SCHED_POLICY_BALANCE)
> + return sprintf(buf, "balance\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 if (!strcmp(str_policy, "balance"))
> + sched_policy = SCHED_POLICY_BALANCE;
> + else
> + return -EINVAL;
> +
> + return count;
> +}
> +
> +/*
> + * * Sysfs setup bits:
> + * */

Unneeded asterisks.

Thanks,
Namhyung


> +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);
> +}
> +
> +static int __init sched_policy_sysfs_init(void)
> +{
> + return create_sysfs_sched_policy_group(cpu_subsys.dev_root);
> +}
> +
> +core_initcall(sched_policy_sysfs_init);
> +#endif /* CONFIG_SYSFS */
> +
> /*
> * All the scheduling class methods:
> */


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