Ceph's systemd unit files currently include the "TasksMax" setting, explained at
RHEL 7.2's systemd does not support this setting, so currently Ceph's service units print warnings about it (described in bz 1335586).
I'm opening this RFE to find out if RHEL 7's systemd will ever support TasksMax and DefaultTasksAccounting.
If RHEL 7's systemd *will* support TasksMax and DefaultTasksAccounting, then Ceph will need to set TasksMax=infinity at that time.
If RHEL 7's systemd *will not* support TasksMax and DefaultTasksAccounting in the future, then it is safe for Ceph to remove the TasksMax setting downstream for RHEL 7.
Will RHEL 7's systemd backport this feature? (Personally this does not seem like a good thing to introduce in RHEL 7, since it will introduce a behavior change of restricting services like this.)
Maybe we should play safe here and just remove that from ceph unit-file. The TasksMax is not even in fedora 23, so it is a really fresh feature.
The ceph-common contains client packages, only (no daemons, no unit files). Also, we already have a downstream RHCEPH bz1335586 for the warning about TasksMax missing in RHEL. This was just a plain RFE for some future RHEL release (7.4 or 7.5, maybe?) to introduce these options for us -> moving back.
Ok so lets postpone it for now.
Let me rephrase my previous comment:
We are quite happy the way it is, now. Let's use this bz as a remainder to inform us (RHCEPH) when (or if) there will be any behaviour change in this area in RHEL.
Lukáš, it sounds like this will probably never be backported to RHEL 7?
If we will backport this to rhel then with infinity as a default settings, so you should be fine in either case.
Note that functionality realized by TasksMax is actually enabled by kernel's "pids" cgroup controller. This controller is not part of RHEL kernel because it was introduced quite recently. In order for us to backport this to systemd we first need pids controller backported to kernel. IIRC, patch introducing pids contoller wasn't very big so it should be easy to backport.
pids cgroup controller is in kernel 3.10.0-372 or later.
I've already backported necessary patches. Feel free to try out test build
fix merged to upstream staging branch ->
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.