[systemd-devel] Query on libpam-systemd

[Lennart Poettering]

On Fri, 29.01.16 11:38, pavi1729 (pavitra1729 at gmail.com) wrote:

> Hi,
>   I have an issue with libpam-systemd which is interfering with
> scheduler settings on my machine. Details as below
> 
> --------------------------------------------------------------------------
> File: linux/kernel/sched/core.c
> 
> WITHOUT libpam-systemd
> 
> [   36.278241] rt_bandwidth_enabled(): 1
> [   36.281977] rt_policy(policy) : 1
> [   36.285367] task_group_is_autogroup(task_group(p)) : 0
> [   36.289883] task_group(p)->rt_bandwidth.rt_runtime : 950000000
> 
> 
> WITH libpam-systemd INSTALLED
> 
> [ 2096.713855] rt_bandwidth_enabled(): 1
> [ 2096.717871] rt_policy(policy) : 1
> [ 2096.721408] task_group_is_autogroup(task_group(p)) : 0
> [ 2096.726180] task_group(p)->rt_bandwidth.rt_runtime: 0  <-- (gets set to 0)
> 
> 
> QUESTION: Why is libpam-systemd setting
> task_group(p)->rt_bandwidth.rt_runtime to 0 ?

We aren't. But we do potentially make use of the "cpu" cgroup
controller...

Note that we generally recommend turning of the RT group sched stuff
for cgroups in the cpu controller, and only leave the non-RT stuff
on. The RT-stuff is kinda borked, non-hierarchal and cannot reasonably
be initialized to any sensible values by default. 

Or in other words: RT is weird if you mix systemd and CONFIG_RT_GROUP_SCHED.

Lennart

-- 
Lennart Poettering, Red Hat