• Peter Zijlstra's avatar
    sched/topology: Fix building of overlapping sched-groups · 0372dd27
    Peter Zijlstra authored
    When building the overlapping groups, we very obviously should start
    with the previous domain of _this_ @cpu, not CPU-0.
    
    This can be readily demonstrated with a topology like:
    
      node   0   1   2   3
        0:  10  20  30  20
        1:  20  10  20  30
        2:  30  20  10  20
        3:  20  30  20  10
    
    Where (for example) CPU1 ends up generating the following nonsensical groups:
    
      [] CPU1 attaching sched-domain:
      []  domain 0: span 0-2 level NUMA
      []   groups: 1 2 0
      []   domain 1: span 0-3 level NUMA
      []    groups: 1-3 (cpu_capacity = 3072) 0-1,3 (cpu_capacity = 3072)
    
    Where the fact that domain 1 doesn't include a group with span 0-2 is
    the obvious fail.
    
    With patch this looks like:
    
      [] CPU1 attaching sched-domain:
      []  domain 0: span 0-2 level NUMA
      []   groups: 1 0 2
      []   domain 1: span 0-3 level NUMA
      []    groups: 0-2 (cpu_capacity = 3072) 0,2-3 (cpu_capacity = 3072)
    Debugged-by: default avatarLauro Ramos Venancio <lvenanci@redhat.com>
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-kernel@vger.kernel.org
    Cc: stable@vger.kernel.org
    Fixes: e3589f6c ("sched: Allow for overlapping sched_domain spans")
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    0372dd27
topology.c 39.9 KB