Re: [PATCH, v7] cgroups: introduce timer slack controller

From: Li Zefan
Date: Thu Mar 03 2011 - 01:57:39 EST


>> +unsigned long get_task_timer_slack(struct task_struct *tsk)
>> +{
>> + struct cgroup_subsys_state *css;
>> + struct tslack_cgroup *tslack_cgroup;
>> + unsigned long ret;
>> +
>> + rcu_read_lock();
>
> Did you just remove the odd comment or actually figure out why you
> need rcu_read_lock() here ?
>

It's necessary to protect against task exiting or task moving between cgroups.

>> + css = task_subsys_state(tsk, timer_slack_subsys.subsys_id);
>> + tslack_cgroup = container_of(css, struct tslack_cgroup, css);
>> + ret = max(tsk->timer_slack_ns, tslack_cgroup->min_slack_ns);
>> + rcu_read_unlock();
>> +
>> + return ret;
>> +}
>
> Otherwise, it's way more palatable than the last one.
>
> Thanks,
>
> tglx
>
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