Re: [RFC] cgroup TODOs

From: Peter Zijlstra
Date: Fri Sep 14 2012 - 07:18:03 EST

On Thu, 2012-09-13 at 13:58 -0700, Tejun Heo wrote:
> The cpu ones handle nesting correctly - parent's accounting includes
> children's, parent's configuration affects children's unless
> explicitly overridden, and children's limits nest inside parent's.

The implementation has some issues with fixed point math limitations on
deep hierarchies/large cpu count, but yes.

Doing soft-float/bignum just isn't going to be popular I guess ;-)

People also don't seem to understand that each extra cgroup carries a
cost and that nested cgroups are more expensive still, even if the
intermediate levels are mostly empty (libvirt is a good example of how
not to do things).

Anyway, I guess what I'm saying is that we need to work on the awareness
of cost associated with all this cgroup nonsense, people seem to think
its all good and free -- or not think at all, which, while depressing,
seem the more likely option.
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