Re: [rfc][patch] DriverFS Topology + per-node (NUMA) meminfo

Rusty Russell (rusty@rustcorp.com.au)
Tue, 29 Oct 2002 10:24:52 +1100


In message <3DBD88EA.7000402@us.ibm.com> you write:
> Rusty Russell wrote:
> > On Mon, 21 Oct 2002 14:50:25 -0700
> > Matthew Dobson <colpatch@us.ibm.com> wrote:
> >
> >
> >>[ patch ]
> >
> >
> > This clashes with my "move cpu driverfs to generic code" patch.
>
> Yes, yes it does. It does a lot of similar things though.

Hey, great minds think alike 8)

> My patch does not take advantage of the DECLARE_PER_CPU macros, etc.

A minor optimization which can be done later. The important bit is
not creating entries for cpus where !cpu_possible(cpu).

> But it also
> offers node-topology info and per-node meminfo. I'd like to see them
> work together. Most of the conflict is simply in where we put the
> driverfs CPU code. Your patch moves it (w/ additions) to kernel/cpu.c,
> whereas mine moves it (also w/ different additions) to
> drivers/base/cpu.c. I think that the drivers/base is a bit more
> appropriate for the driverfs specific code (struct device_driver
> cpu_driver, the array of cpu_devices...). Also, I made the registration
> routines arch-specific, because I figured that different architectures
> may want to add arch-specific info, and register devices at different
> times, in different orders, etc. I also didn't incorporate the
> cpu_notifier stuff, which I should have.
>
> What do you think of my patch (other than the obvious that it conflicts
> with yours)?

If I'm reading correctly, you move the cpus under "node" dirs when
it's a NUMA system. I can see the cute appeal, but it makes it harder
to answer "how many cpus do I have?": a program would need to do a
"find" which is kinda icky (also hard to write HOWTOs). So I'd prefer
symlinks to the node, and no hierarchy.

driver/base/cpu.c should probably be moved into kernel/cpu.c anyway.

I think exposing the struct cpu array is a good idea, so archs can add
properties if they want (ie. node information).

But Patrick is the architect, I'm just a grunt, so it's his call 8)
Rusty.

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