From 7bd953206b0b5e0a3aded871982367410b42e1b1 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Fri, 17 Oct 2014 03:29:51 -0400 Subject: [PATCH] sched/numa: Prepare for complex topology placement Preparatory patch for adding NUMA placement on systems with complex NUMA topology. Also fix a potential divide by zero in group_weight() Signed-off-by: Rik van Riel Tested-by: Chegu Vinod Signed-off-by: Peter Zijlstra (Intel) Cc: mgorman@suse.de Cc: chegu_vinod@hp.com Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1413530994-9732-4-git-send-email-riel@redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 57 +++++++++++++++++++++++++++++---------------- 1 file changed, 37 insertions(+), 20 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 34baa60f8a7b..0af3bed3521d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -931,9 +931,10 @@ static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) * larger multiplier, in order to group tasks together that are almost * evenly spread out between numa nodes. */ -static inline unsigned long task_weight(struct task_struct *p, int nid) +static inline unsigned long task_weight(struct task_struct *p, int nid, + int dist) { - unsigned long total_faults; + unsigned long faults, total_faults; if (!p->numa_faults_memory) return 0; @@ -943,15 +944,25 @@ static inline unsigned long task_weight(struct task_struct *p, int nid) if (!total_faults) return 0; - return 1000 * task_faults(p, nid) / total_faults; + faults = task_faults(p, nid); + return 1000 * faults / total_faults; } -static inline unsigned long group_weight(struct task_struct *p, int nid) +static inline unsigned long group_weight(struct task_struct *p, int nid, + int dist) { - if (!p->numa_group || !p->numa_group->total_faults) + unsigned long faults, total_faults; + + if (!p->numa_group) return 0; - return 1000 * group_faults(p, nid) / p->numa_group->total_faults; + total_faults = p->numa_group->total_faults; + + if (!total_faults) + return 0; + + faults = group_faults(p, nid); + return 1000 * faults / total_faults; } bool should_numa_migrate_memory(struct task_struct *p, struct page * page, @@ -1084,6 +1095,7 @@ struct task_numa_env { struct numa_stats src_stats, dst_stats; int imbalance_pct; + int dist; struct task_struct *best_task; long best_imp; @@ -1163,6 +1175,7 @@ static void task_numa_compare(struct task_numa_env *env, long load; long imp = env->p->numa_group ? groupimp : taskimp; long moveimp = imp; + int dist = env->dist; rcu_read_lock(); @@ -1196,8 +1209,8 @@ static void task_numa_compare(struct task_numa_env *env, * in any group then look only at task weights. */ if (cur->numa_group == env->p->numa_group) { - imp = taskimp + task_weight(cur, env->src_nid) - - task_weight(cur, env->dst_nid); + imp = taskimp + task_weight(cur, env->src_nid, dist) - + task_weight(cur, env->dst_nid, dist); /* * Add some hysteresis to prevent swapping the * tasks within a group over tiny differences. @@ -1211,11 +1224,11 @@ static void task_numa_compare(struct task_numa_env *env, * instead. */ if (cur->numa_group) - imp += group_weight(cur, env->src_nid) - - group_weight(cur, env->dst_nid); + imp += group_weight(cur, env->src_nid, dist) - + group_weight(cur, env->dst_nid, dist); else - imp += task_weight(cur, env->src_nid) - - task_weight(cur, env->dst_nid); + imp += task_weight(cur, env->src_nid, dist) - + task_weight(cur, env->dst_nid, dist); } } @@ -1314,7 +1327,7 @@ static int task_numa_migrate(struct task_struct *p) }; struct sched_domain *sd; unsigned long taskweight, groupweight; - int nid, ret; + int nid, ret, dist; long taskimp, groupimp; /* @@ -1342,12 +1355,13 @@ static int task_numa_migrate(struct task_struct *p) return -EINVAL; } - taskweight = task_weight(p, env.src_nid); - groupweight = group_weight(p, env.src_nid); - update_numa_stats(&env.src_stats, env.src_nid); env.dst_nid = p->numa_preferred_nid; - taskimp = task_weight(p, env.dst_nid) - taskweight; - groupimp = group_weight(p, env.dst_nid) - groupweight; + dist = env.dist = node_distance(env.src_nid, env.dst_nid); + taskweight = task_weight(p, env.src_nid, dist); + groupweight = group_weight(p, env.src_nid, dist); + update_numa_stats(&env.src_stats, env.src_nid); + taskimp = task_weight(p, env.dst_nid, dist) - taskweight; + groupimp = group_weight(p, env.dst_nid, dist) - groupweight; update_numa_stats(&env.dst_stats, env.dst_nid); /* Try to find a spot on the preferred nid. */ @@ -1359,12 +1373,15 @@ static int task_numa_migrate(struct task_struct *p) if (nid == env.src_nid || nid == p->numa_preferred_nid) continue; + dist = node_distance(env.src_nid, env.dst_nid); + /* Only consider nodes where both task and groups benefit */ - taskimp = task_weight(p, nid) - taskweight; - groupimp = group_weight(p, nid) - groupweight; + taskimp = task_weight(p, nid, dist) - taskweight; + groupimp = group_weight(p, nid, dist) - groupweight; if (taskimp < 0 && groupimp < 0) continue; + env.dist = dist; env.dst_nid = nid; update_numa_stats(&env.dst_stats, env.dst_nid); task_numa_find_cpu(&env, taskimp, groupimp);