On Aug 8, 2008, at 5:35 PM, Jeff Squyres (jsquyres) wrote:
> --> We know that linux processor ID's can have holes. I am pretty
> sure that socket IDs can have holes, too. I'm not sure if core IDs
> can have holes, but I guess it's conceivable that in the manycore
> world, you could have a socket where 1 core is dead and other cores
> are fine...?
>
To answer my own question, yes, core IDs *can* have holes -- one case
is if you manually take a processor offline. E.g., if you have a 4
core socket and take core 1 offline (e.g., "echo 0 > /sys/devices/
system/cpu/cpu1/online"), cores 0, 2, and 3 are still reported by the
kernel.
The bummer is that when you manually take a processor offline, the
kernel no longer reports that processor's topology information (@#$@#
$), so PLPA has no idea what (socket_id,core_id) it belongs to.
--
Jeff Squyres
Cisco Systems
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