Re: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes

[Oleg Nesterov]

On 07/14, Peter Zijlstra wrote:
>
> But I really think that this Android usecase invalidates the premise of
> cgroups using a global lock.

Perhaps... but it would be nice to have a global lock for cgroups (and in
fact probably unify it with dup_mmap_sem). And we can't simply revert that
change now.

I am wondering if this use-case is really Android-specific or not. Because,
once again, we can add a boot option or even run-time knob for
cgroup_threadgroup_rwsem. If it is really Android-specific, we do not want
to penalize fork/exit by default.

Oleg.