x86: Set cpu_llc_id on AMD CPUs

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This counts when building sched domains in case NUMA information
is not available.

( See cpu_coregroup_mask() which uses llc_shared_map which in turn is
  created based on cpu_llc_id. )

Currently Linux builds domains as follows:
(example from a dual socket quad-core system)

 CPU0 attaching sched-domain:
  domain 0: span 0-7 level CPU
   groups: 0 1 2 3 4 5 6 7

  ...

 CPU7 attaching sched-domain:
  domain 0: span 0-7 level CPU
   groups: 7 0 1 2 3 4 5 6

Ever since that is borked for multi-core AMD CPU systems.
This patch fixes that and now we get a proper:

 CPU0 attaching sched-domain:
  domain 0: span 0-3 level MC
   groups: 0 1 2 3
   domain 1: span 0-7 level CPU
    groups: 0-3 4-7

  ...

 CPU7 attaching sched-domain:
  domain 0: span 4-7 level MC
   groups: 7 4 5 6
   domain 1: span 0-7 level CPU
    groups: 4-7 0-3

This allows scheduler to assign tasks to cores on different sockets
(i.e. that don't share last level cache) for performance reasons.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
LKML-Reference: <20090619085909.GJ5218@alberich.amd.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

This commit is contained in:

Andreas Herrmann 2009-06-19 10:59:09 +02:00 • committed by Ingo Molnar

parent c277331d5f

commit 99bd0c0fc4

1 changed files with 3 additions and 1 deletions

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arch/x86/kernel/cpu/amd.c

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