Re: [RFC][PATCH] powerpc: respect how command line nr_cpus is set

On May 4, 2011, at 9:25 PM, Benjamin Herrenschmidt wrote:

On Wed, 2011-05-04 at 15:17 -0500, Kumar Gala wrote:

quoted

We should utilize nr_cpus as the max # of CPUs that we can have =

present

quoted

instead of NR_CPUS.  This way we actually respect how nr_cpus is set =

on

quoted

the command line rather than ignoring it.
=20
Signed-off-by: Kumar Gala <redacted>
---
I think this is what we should be doing, but would like someone else =

to take

quoted

a look.

=20
The main question I have is should max_cpus absolutely limit the =

number

of possible CPUs or should it limit the number that get automatically
onlined at boot, potentially letting us bring the rest online later on =

?

=20
Cheers,
Ben.

=46rom Documentation/kernel-parameters.txt:

        nr_cpus=3D        [SMP] Maximum number of processors that an SMP =
kernel
                        could support.  nr_cpus=3Dn : n >=3D 1 limits =
the kernel to
                        supporting 'n' processors. Later in runtime you =
can not
                        use hotplug cpu feature to put more cpu back to =
online.
                        just like you compile the kernel NR_CPUS=3Dn

Which makes me think we should have max_cpus be an absolute limit.

- k=