Re: regression introduced by - timers: fix itimer/many thread hang

[Peter Zijlstra <peterz@infradead.org>]

On Thu, 2008-11-06 at 09:03 -0600, Christoph Lameter wrote:
> On Thu, 6 Nov 2008, Peter Zijlstra wrote:
> 
> > Also, you just introduced per-cpu allocations for each thread-group,
> > while Christoph is reworking the per-cpu allocator, with one unfortunate
> > side-effect - its going to have a limited size pool. Therefore this will
> > limit the number of thread-groups we can have.
> 
> Patches exist that implement a dynamically growable percpu pool (using
> virtual mappings though). If the cost of the additional complexity /
> overhead is justifiable then we can make the percpu pool dynamically
> extendable.

Right, but I don't think the patch under consideration will fly anyway,
doing a for_each_possible_cpu() loop on every tick on all cpus isn't
really healthy, even for moderate sized machines.