Re: [RFC][PATCH] NOOP cgroup subsystem

From: Paul Menage
Date: Tue Jan 20 2009 - 22:17:01 EST


On Mon, Jan 19, 2009 at 7:07 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> In my understanding, "sending signal" requires some protocol/order in userland.
>
> Assume that users has to send signal in following order
> Application A -> Application B -> Application C.....
> and may have problems sending signals in following order
> Application B -> Application A ->.....

In a case like that, a user would have to do their own signal sending
rather than letting the "signal" subsystem handle it. The signal
subsystem is more useful for doing things like sending less-refined
signals like SIGSTOP or SIGKILL to all tasks in a cgroup.

> multilply-mounted means its own hierachy can be created per mount point ?

Yes.

> If so, signal subsystem can be used instead of noop.

Supporting mounting a subsystem in multiple different hierarchies
would pretty much involve supporting mounting a hierarchy with no
subsystems (at least in the way I envisaged it), so you wouldn't need
any subsystem in that case if you were just trying to do grouping.

Paul
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