Unfortunately, due to the disagreements in the kernel development community, CPU controller cgroup v2 support has not been merged and enabling it requires applying two small out-of-tree kernel patches. The situation is explained in the following documentation: https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu While it isn't clear what will happen with CPU controller cgroup v2 support, there are critical features which are possible only on cgroup v2 such as buffered write control making cgroup v2 essential for a lot of workloads. Also we finally have reliable empty cgroup reporting which avoids various systemd issues with zombie scope units and such. Systemd recently gained experimental support for the new cgroup v2 cpu controller [1], which of course only works for people who a) are running with systemd.unified_cgroup_hierarchy=1 and b) have a patched kernel. We would like to move closer towards switching to v2 hierarchy, with an eye towards using unified hierarchy by default, but we have a chicken and egg problem where we cannot encourage people to switch and test systemd with v2 hierarchy, since the kernel support is incomplete. And the kernel support does not get enough testing because it's incomplete and requires a substantive effort. Would it be possible to compile the rawhide kernels with the cgroup-v2-cpu patches [2]? This should cause no issue for v1 users, and would let the kernel and systemd functionality get wider testing, and hopefully nudge the kernel upstream towards finalizing the unified hierarchy support. Zbyszek [1] https://github.com/systemd/systemd/commit/5f9a610ad2b3200a3 [2] https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/log/?h=cgroup-v2-cpu _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://lists.fedoraproject.org/admin/lists/kernel@xxxxxxxxxxxxxxxxxxxxxxx
