Re: [RFC] Scalable statistics counters using kmalloc_percpu

[Rusty Russell]

> > +       for( i=0; i < NR_CPUS; i++ )
> > +               res += *per_cpu_ptr(stctr->ctr, i);
> > +       return res;
> > +}
> 
> Oh dear.  Most people only have two CPUs.
> 
> Rusty, can we *please* fix this?  Really soon?

Linus just applied the hotplug cpu boot patch in bk, which gives
cpu_possible(i), for exactly this purpose.

> General comment:  we need to clean up the kernel_stat stuff.  We
> cannot just make it per-cpu because it is 32k in size already.  I
> would suggest that we should break out the disk accounting and
> make the rest of kernel_stat per CPU.

kernel_stat is dynamically allocated???

Personally, I think that dynamically allocated per-cpu datastructures,
like dynamically-allocated brlocks, are something we might need
eventually, but look at what a certain driver did with the "make it
per-cpu" concept already.  I don't want to rush in that direction.

Cheers,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.