Messages in this thread | | | Date | Fri, 2 May 2008 12:53:04 -0700 | From | Andrew Morton <> | Subject | Re: [RFC][-mm] Simple stats for cpu resource controller v3 |
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On Sat, 3 May 2008 01:10:28 +0530 Balaji Rao <balajirrao@gmail.com> wrote:
> On Friday 02 May 2008 02:30:26 am Andrew Morton wrote: > <snip> > > Hi Andrew, > > Thank you for the review. > > > > Did you consider using include/linux/percpu_counter.h? > > > > If so, what was wrong with it? > > > > Because it would be much better to fix per-cpu counters than to invent new > > stuff. > No, I hadn't consider using the percpu_counters infrastructure. But today when > I tried using it, I got an early exception.I guess its because I tried > calling percpu_counter_init from within sched_init, which I perhaps shouldn't > do, because percpu_counter_init expects cpu hotplug code to be initialized by > then. Right ? Correct me if I'm wrong.
I don't see any reason why we cannot run percpu_counter_init() prior to running percpu_counter_startup(). And it is desirable that we be able to start using the percpu-counters quite early.
Can you debug it a bit please? It's probably some silly little thing, perhaps fixable by calling percpu_counter_startup() earlier.
> How about we start collecting statistics at a later stage i.e, after > percpu_counter becomes usable ?
It would be better to make the core infrastructure more robust, rather than working around problems it might have.
It's rather nice that percpu_counters internally take care of cpu-hotplugging, and use cpu_online_map. I was amazed at how easily that was added. I still expect it to break somehow..
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