Re: [HTCondor-users] ENOENT writing to cgroup.subtree_control, but file exists

[KÃhn, Max (SCC) <max.fischer@xxxxxxx>]

Hi all,

TLDR: We know whatâs triggering this and thereâs an obvious workaround. But weâre not sure whatâs the âproperâ way of running HTCondor with cgroupv2.

We did a bit of digging, the error from HTCondor is âcorrectâ just misleading. Even manually replicating the situation leads to the same error:

	$ echo "+cpu +io +memory +pids" > /sys/fs/cgroup/htcondor/cgroup.subtree_control
	-bash: echo: write error: No such file or directory

For whatever reason, our systems consistently have only âmemory pidsâ in /sys/fs/cgroup/cgroup.subtree_control. So thereâs a few pseudo-files missing for the cpu and io controllers, which kinda makes ENOENT appropriate.
Manually updating /sys/fs/cgroup/cgroup.subtree_control then makes HTCondorâs cgroup manipulation work. So a quick echo on boot is a workaround for now...

Does anyone know what is HTCondor's expected state for this? RH claims our state is the default on RHEL8 and RHEL9 [0,1]. Should the system, e.g. systemd, have enabled the controllers (RHEL8 ships with the dated systemd 239)? Should the BASE_CGROUP already be prepared with the appropriate controllers?

Cheers,
Max

[0] https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/managing_monitoring_and_updating_the_kernel/assembly_using-cgroupfs-to-manually-manage-cgroups_managing-monitoring-and-updating-the-kernel#proc_creating-cgroups-and-enabling-controllers-in-cgroups-v2-file-system_assembly_using-cgroupfs-to-manually-manage-cgroups

[1] https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/managing_monitoring_and_updating_the_kernel/using-cgroups-v2-to-control-distribution-of-cpu-time-for-applications_managing-monitoring-and-updating-the-kernel#using-cgroups-v2-to-control-distribution-of-cpu-time-for-applications_managing-monitoring-and-updating-the-kernel


> On 8. Jul 2024, at 15:22, Matthias Schnepf <matthias.schnepf@xxxxxxx> wrote:
> 
> Hi Christoph,
> 
> It also happens when SE-Linux is disabled.
> 
> Cheers,
> 
> Matthias
> 
> On 7/8/24 13:39, Beyer, Christoph wrote:
>> Hi Max,
>> 
>> could this be related to SE-Linux ?
>> 
>> Best
>> christoph
>> 
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