Messages in this thread | | | Date | Tue, 26 Jul 2022 16:32:57 +0200 | From | Michal Koutný <> | Subject | Re: [PATCH RESEND 3/3 cgroup/for-5.20] cgroup: Make !percpu threadgroup_rwsem operations optional |
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On Sat, Jul 23, 2022 at 04:28:28AM -1000, Tejun Heo <tj@kernel.org> wrote: > This makes the hotter paths - fork and exit - slower as they're always > forced into the slow path. There is no reason to force this on everyone > especially given that more common static usage pattern can now completely > avoid write-locking the rwsem. Write-locking is elided when turning on and > off controllers on empty sub-trees and CLONE_INTO_CGROUP enables seeding a > cgroup without grabbing the rwsem.
Just a practical note that CLONE_INTO_CGROUP may not be so widespread yet [1][2]. But generally, the change makes sense to me.
> + CGRP_ROOT_FAVOR_DYNMODS = (1 << 4), > + > + /* > * Enable cpuset controller in v1 cgroup to use v2 behavior. > */ > - CGRP_ROOT_CPUSET_V2_MODE = (1 << 4), > + CGRP_ROOT_CPUSET_V2_MODE = (1 << 16), > > /* > * Enable legacy local memory.events. > */ > - CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 5), > + CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 17), > > /* > * Enable recursive subtree protection > */ > - CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 6), > + CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 18),
Why this new gap in flag bits?
[1] https://github.com/systemd/systemd/pull/16706 [2] https://github.com/search?q=org%3Aopencontainers+CLONE_INTO_CGROUP&type=all (empty) [unhandled content-type:application/pgp-signature] | |