From: Mike Galbraith commit 50b926e439620c469565e8be0f28be78f5fca1ce upstream SD_PREFER_SIBLING is set at the CPU domain level if power saving isn't enabled, leading to many cache misses on large machines as we traverse looking for an idle shared cache to wake to. Change the enabler of select_idle_sibling() to SD_SHARE_PKG_RESOURCES, and enable same at the sibling domain level. Reported-by: Lin Ming Signed-off-by: Mike Galbraith Signed-off-by: Peter Zijlstra LKML-Reference: <1262612696.15495.15.camel@marge.simson.net> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- include/linux/topology.h | 2 +- kernel/sched_fair.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -99,7 +99,7 @@ int arch_update_cpu_topology(void); | 1*SD_WAKE_AFFINE \ | 1*SD_SHARE_CPUPOWER \ | 0*SD_POWERSAVINGS_BALANCE \ - | 0*SD_SHARE_PKG_RESOURCES \ + | 1*SD_SHARE_PKG_RESOURCES \ | 0*SD_SERIALIZE \ | 0*SD_PREFER_SIBLING \ , \ --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1490,7 +1490,7 @@ select_task_rq_fair(struct rq *rq, struc * If there's an idle sibling in this domain, make that * the wake_affine target instead of the current cpu. */ - if (tmp->flags & SD_PREFER_SIBLING) + if (tmp->flags & SD_SHARE_PKG_RESOURCES) target = select_idle_sibling(p, tmp, target); if (target >= 0) {