Andrew Morton wrote:
>
> Rusty Russell wrote:
> >
> > ...
> > Let's not perpetuate the myth that everything in the kernel needs to
> > be tuned to the last cycle at all costs, hm?
>
> I was more concerned about the RAM use, actually.
>
> This patch is an additional reason for CONFIG_NR_CPUS, but I've rather
> gone cold on that idea because the "proper fix" is to make all those
> huge per-cpu arrays dynamically allocated. So you can run a 64p kernel
> on 2p without losing hundreds of k of memory and kernel address space.
>
> But it looks like all those dynamically-allocated structures would
> have to be allocated out to NR_CPUS anyway, to support hotplug, yes?
>
> In which case, CONFIG_NR_CPUS is the only way to get the memory
> back...
Re-allocation of tables when adding CPUs is another
option. That means the data moves - so others have to store
array indices instead of direct pointers to stuff they use.
Dynamic allocation not merely at boottime, but everytime.
Adding a CPU becomes more expensive, but that won't
happen hundreds of times a second anyway.
Helge Hafting
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This archive was generated by hypermail 2b29 : Sat Jun 15 2002 - 22:00:24 EST