From c22402a2f76e88b04b7a8b6c0597ad9ba6fd71de Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 20 Apr 2012 16:57:22 +0200 Subject: [PATCH] sched/fair: Let minimally loaded cpu balance the group Currently we let the leftmost (or first idle) cpu ascend the sched_domain tree and perform load-balancing. The result is that the busiest cpu in the group might be performing this function and pull more load to itself. The next load balance pass will then try to equalize this again. Change this to pick the least loaded cpu to perform higher domain balancing. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-v8zlrmgmkne3bkcy9dej1fvm@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 678966ca393b..968ffee24721 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3781,7 +3781,8 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, { unsigned long load, max_cpu_load, min_cpu_load, max_nr_running; int i; - unsigned int balance_cpu = -1, first_idle_cpu = 0; + unsigned int balance_cpu = -1; + unsigned long balance_load = ~0UL; unsigned long avg_load_per_task = 0; if (local_group) @@ -3797,12 +3798,11 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, /* Bias balancing toward cpus of our domain */ if (local_group) { - if (idle_cpu(i) && !first_idle_cpu) { - first_idle_cpu = 1; + load = target_load(i, load_idx); + if (load < balance_load || idle_cpu(i)) { + balance_load = load; balance_cpu = i; } - - load = target_load(i, load_idx); } else { load = source_load(i, load_idx); if (load > max_cpu_load) {