Re: [PATCH v3 14/22] sched: add sched_policy and it's sysfs interface

[Alex Shi <alex.shi@intel.com>]

On 01/14/2013 02:53 PM, Namhyung Kim wrote:
> Hi Alex,
> 
> Just a few nitpickings..

Got it. Thanks a lot!
> 
> 
> 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:
>>   */


-- 
Thanks Alex