• Peter Zijlstra's avatar
    sched/topology: Restore SD_PREFER_SIBLING on MC domains · ed4ad1ca
    Peter Zijlstra authored
    The normal x86_topology on NHM+ machines degenerates because the MC
    and CPU domains are of the same size, therefore MC inherits
    SD_PREFER_SIBLING from CPU (which then gets taken out). The result is
    that we'll spread tasks across the first NUMA level in order to
    maximize cache utilization.
    
    However, for the x86_numa_in_package_topology we loose the CPU domain,
    and we'll not have SD_PREFER_SIBLING set anywhere, giving a distinct
    difference in behaviour.
    
    Commit:
    
      8e7fbcbc ("sched: Remove stale power aware scheduling remnants and dysfunctional knobs")
    
    made a fail by not preserving the SD_PREFER_SIBLING for the !power_saving
    case on both CPU and MC.
    
    Then commit:
    
      6956dc56 ("sched/numa: Add SD_PERFER_SIBLING to CPU domain")
    
    adds it back to the CPU but not MC.
    
    Restore that now, such that we get consistent spreading behaviour wrt
    L3 and NUMA.
    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
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    ed4ad1ca
topology.c 47.2 KB