Messages in this thread | | | Date | Tue, 26 Jul 2022 07:33:22 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH RESEND 3/3 cgroup/for-5.20] cgroup: Make !percpu threadgroup_rwsem operations optional |
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Hello,
On Tue, Jul 26, 2022 at 04:32:57PM +0200, Michal Koutný wrote: > 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.
Yeah, I was disappoinetd that it wasn't being used by systemd already. It'd be great if the glibc situation can be rectified soon because this is a much better interface.
> > + 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?
To distinguish core and per-controller flags.
Thanks.
-- tejun
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