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Date: Mon, 14 Jan 2013 16:11:21 +0800
From: Alex Shi <alex.shi@...el.com>
To: Namhyung Kim <namhyung@...nel.org>
CC: mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de,
akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
pjt@...gle.com, efault@....de, vincent.guittot@...aro.org,
gregkh@...uxfoundation.org, preeti@...ux.vnet.ibm.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 14/22] sched: add sched_policy and it's sysfs interface
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@...el.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@...r.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@...ck.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
--
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