Back off slowly from scanning, up to sysctl_sched_numa_scan_period_max (1.6 seconds). Scan faster again if we were forced to switch to another node.
This makes sure that workload in equilibrium don't get scanned as often as workloads that are still converging. Cc: Peter Zijlstra <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Hugh Dickins <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/core.c | 6 ++++++ kernel/sched/fair.c | 8 +++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8ef9a46..39cf991 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6029,6 +6029,12 @@ void sched_setnuma(struct task_struct *p, int node, int shared) if (on_rq) enqueue_task(rq, p, 0); task_rq_unlock(rq, p, &flags); + + /* + * Reset the scanning period. If the task converges + * on this node then we'll back off again: + */ + p->numa_scan_period = sysctl_sched_numa_scan_period_min; } #endif /* CONFIG_NUMA_BALANCING */ diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8f0e6ba..59fea2e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -865,8 +865,10 @@ static void task_numa_placement(struct task_struct *p) } } - if (max_node != p->numa_max_node) + if (max_node != p->numa_max_node) { sched_setnuma(p, max_node, task_numa_shared(p)); + goto out_backoff; + } p->numa_migrate_seq++; if (sched_feat(NUMA_SETTLE) && @@ -882,7 +884,11 @@ static void task_numa_placement(struct task_struct *p) if (shared != task_numa_shared(p)) { sched_setnuma(p, p->numa_max_node, shared); p->numa_migrate_seq = 0; + goto out_backoff; } + return; +out_backoff: + p->numa_scan_period = min(p->numa_scan_period * 2, sysctl_sched_numa_scan_period_max); } /* -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
