Messages in this thread | | | Date | Fri, 14 Oct 2011 15:43:48 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH, v10 3/3] cgroups: introduce timer slack controller |
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On Tue, 11 Oct 2011 19:15:29 +0300 "Kirill A. Shutemov" <kirill@shutemov.name> wrote:
> Every task_struct has timer_slack_ns value. This value uses to round up > poll() and select() timeout values. This feature can be useful in > mobile environment where combined wakeups are desired. > > Originally, prctl() was the only way to change timer slack value of > a process. So you was not able change timer slack value of another > process. > > cgroup subsys "timer_slack" implements timer slack controller. It > provides a way to set minimal timer slack value for a group of tasks. > If a task belongs to a cgroup with minimal timer slack value higher than > task's value, cgroup's value will be applied. > > Timer slack controller allows to implement setting timer slack value of > a process based on a policy. For example, you can create foreground and > background cgroups and move tasks between them based on system state.
I'm having trouble understanding the value of this feature. Users can presently control the timer-slack of a group of processes via inherit-over-fork.
Perhaps there's a case for providing a way for process A to set process B's slack. And perhaps B's children. That would be a simpler patch and would have the considerable advantage that it doesn't require cgroups.
So.... why should we merge this?
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