Leverage SD_DEGENERATE_GROUPS_MASK in sd_degenerate() and sd_degenerate_parent().
Note that this changes sd_degenerate() somewhat: I'm using the negation of SD_DEGENERATE_GROUPS_MASK as the mask of flags not requiring groups, which is equivalent to: SD_WAKE_AFFINE | SD_SERIALIZE | SD_NUMA whereas the current mask for that is simply SD_WAKE_AFFINE I played with a few toy NUMA topologies on QEMU and couldn't cause a different degeneration than what mainline does currently. If that is deemed too risky, we can go back to using SD_WAKE_AFFINE explicitly. Suggested-by: Peter Zijlstra <[email protected]> Signed-off-by: Valentin Schneider <[email protected]> --- kernel/sched/topology.c | 24 +++--------------------- 1 file changed, 3 insertions(+), 21 deletions(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index fe393b295444..a135a0c99b16 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -160,22 +160,13 @@ static int sd_degenerate(struct sched_domain *sd) return 1; /* Following flags need at least 2 groups */ - if (sd->flags & (SD_BALANCE_NEWIDLE | - SD_BALANCE_WAKE | - SD_BALANCE_FORK | - SD_BALANCE_EXEC | - SD_ASYM_PACKING | - SD_SHARE_CPUCAPACITY | - SD_ASYM_CPUCAPACITY | - SD_SHARE_PKG_RESOURCES | - SD_OVERLAP | - SD_PREFER_SIBLING)) { + if (sd->flags & SD_DEGENERATE_GROUPS_MASK) { if (sd->groups != sd->groups->next) return 0; } /* Following flags don't use groups */ - if (sd->flags & (SD_WAKE_AFFINE)) + if (sd->flags & ~SD_DEGENERATE_GROUPS_MASK) return 0; return 1; @@ -194,16 +185,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) /* Flags needing groups don't count if only 1 group in parent */ if (parent->groups == parent->groups->next) { - pflags &= ~(SD_BALANCE_NEWIDLE | - SD_BALANCE_WAKE | - SD_BALANCE_FORK | - SD_BALANCE_EXEC | - SD_ASYM_PACKING | - SD_ASYM_CPUCAPACITY | - SD_SHARE_CPUCAPACITY | - SD_SHARE_PKG_RESOURCES | - SD_OVERLAP | - SD_PREFER_SIBLING); + pflags &= ~SD_DEGENERATE_GROUPS_MASK; if (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; } -- 2.27.0
