From: Peter Zijlstra Date: Fri, 20 Apr 2012 14:57:22 +0000 (+0200) Subject: sched/fair: Let minimally loaded cpu balance the group X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=c22402a2f76e88b04b7a8b6c0597ad9ba6fd71de;p=~shefty%2Frdma-dev.git 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 --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 678966ca393..968ffee2472 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) {