[systemd-devel] [lennart at kemper.freedesktop.org: [systemd-commits] src/pam-module.c]

[Lennart Poettering]

On Mon, 27.12.10 11:05, fykcee1 at gmail.com (fykcee1 at gmail.com) wrote:

> Hi Lennart,
> 
> 2010/12/24 Lennart Poettering <lennart at poettering.net>
> >
> >
> > This is related to the issue reported in LWN about JACK+cgroups. Also,
> > this issue breaks my 4 line bash patch as known from slashdot,
> 
> AIUI, This is not a kernel problem, and is related with
> libcgroup<http://sourceforge.net/projects/libcg/>

Nah, the way I see it it is a kernel problem. The right fix for the
problem in my eyes would be if the kernel cpu controller would be split
into two: one that manages rt time slices (and is never used by
default), and one that manages CPU shares for normally scheduled
processes (which is what sytsemd would use). 

My take on this:

http://article.gmane.org/gmane.comp.audio.jackit/23071

> IMHO, It should be the job of some thing(like systemd) directly play
> with cgroup.  It seems systemd doesn't use libcgroup, am I right?
> Then, It should be fine if systemd grants realtime access to cgroup
> for each user session itself.

The problem is that in systemd we'd like to manage CPU shares for normal
processes, but cannot realistically manage CPU shares for RT
processes. However as the kernel cpu cgroup controller is written right
now, you either have to do both, or neither. And that I believe is very
much broken and should not be tried to worked around but fixed on the
kernel side.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.