Re: slab: start_cpu_timer/cache_reap CONFIG_HOTPLUG_CPU problems

[Max Krasnyansky]

Christoph Lameter wrote:
> On Tue, 20 Feb 2007, Max Krasnyansky wrote:
>
> > I guess I kind of hijacked the thread. The second part of my first email was
> > dropped. Basically I was saying that I'm working on CPU isolation extensions.
> > Where an isolated CPU is not supposed to do much kernel work. In which case
> > you'd want to run slab cache reaper on some other CPU on behalf of the
> > isolated
> > one. Hence the proposal to explicitly pass cpu_id to the reaper. I guess now
> > that you guys fixed the hotplug case it does not help in that scenario.
>
> A cpu must have a per cpu cache in order to do slab allocations. The 
> locking in the slab allocator depends on it.
>
> If the isolated cpus have no need for slab allocations then you will also 
> not need to run the slab_reaper().

Ok. Sounds like disabling cache_reaper is a better option for now. Like you said
it's unlikely that slabs will grow much if that cpu is not heavily used by the
kernel.

Thanks
Max
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