Re: A Plumberâs Wish List for Linux

[Lennart Poettering]

On Sat, 22.10.11 12:21, Frederic Weisbecker (fweisbec@xxxxxxxxx) wrote:

> If you really need to stop any forks in a cgroup, then a cgroup core feature
> handling that very single purpose would be better and more efficient.

We'd be happy with that and this is what we originally suggested actually.

> That said I'm not really sure why you're using cgroups in Systemd.

We want to reliably label processes in a hierarchial way, so that this
is inherited by all child processes, cannot be overriden by unprivileged
code (subject to some classic Unix access control handling) and get
notifications when such a label stops referring to any process. We use
that for sticking the service name on a process, so that all CGI
processes of Apache are automatically assigned the same service as
apache itself. And we want a notification when all of apache's processes
die. And we also want to be able to kill Apache compeltely by killing
all its processes.

cgroups provides us with all of that, though the last two items only in
a suboptimal way: notification of cgroups running empty is ugly, since
it is done by spawning a usermode helper (we'd prefer a netlink msg or
so), and the process killing is a bit racy.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.
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