sched/numa: Reduce conflict between fbq_classify_rq() and migration
It is possible for fbq_classify_rq() to indicate that a CPU has tasks that should be moved to another NUMA node, but for migrate_improves_locality and migrate_degrades_locality to not identify those tasks. This patch always gives preference to preferred node evaluations, and only checks the number of faults when evaluating moves between two non-preferred nodes on a larger NUMA system. On a two node system, the number of faults is never evaluated. Either a task is about to be pulled off its preferred node, or migrated onto it. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mgorman@suse.de Link: http://lkml.kernel.org/r/20150514225936.35b91717@annuminas.surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -5663,10 +5663,15 @@ static int task_hot(struct task_struct *p, struct lb_env *env)
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}
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#ifdef CONFIG_NUMA_BALANCING
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#ifdef CONFIG_NUMA_BALANCING
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/* Returns true if the destination node has incurred more faults */
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/*
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* Returns true if the destination node is the preferred node.
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* Needs to match fbq_classify_rq(): if there is a runnable task
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* that is not on its preferred node, we should identify it.
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*/
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static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
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static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
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{
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{
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struct numa_group *numa_group = rcu_dereference(p->numa_group);
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struct numa_group *numa_group = rcu_dereference(p->numa_group);
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unsigned long src_faults, dst_faults;
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int src_nid, dst_nid;
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int src_nid, dst_nid;
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if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults ||
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if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults ||
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@ -5680,29 +5685,30 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
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if (src_nid == dst_nid)
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if (src_nid == dst_nid)
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return false;
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return false;
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if (numa_group) {
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/* Task is already in the group's interleave set. */
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if (node_isset(src_nid, numa_group->active_nodes))
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return false;
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/* Task is moving into the group's interleave set. */
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if (node_isset(dst_nid, numa_group->active_nodes))
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return true;
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return group_faults(p, dst_nid) > group_faults(p, src_nid);
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}
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/* Encourage migration to the preferred node. */
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/* Encourage migration to the preferred node. */
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if (dst_nid == p->numa_preferred_nid)
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if (dst_nid == p->numa_preferred_nid)
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return true;
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return true;
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return task_faults(p, dst_nid) > task_faults(p, src_nid);
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/* Migrating away from the preferred node is bad. */
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if (src_nid == p->numa_preferred_nid)
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return false;
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if (numa_group) {
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src_faults = group_faults(p, src_nid);
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dst_faults = group_faults(p, dst_nid);
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} else {
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src_faults = task_faults(p, src_nid);
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dst_faults = task_faults(p, dst_nid);
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}
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return dst_faults > src_faults;
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}
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}
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static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
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static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
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{
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{
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struct numa_group *numa_group = rcu_dereference(p->numa_group);
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struct numa_group *numa_group = rcu_dereference(p->numa_group);
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unsigned long src_faults, dst_faults;
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int src_nid, dst_nid;
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int src_nid, dst_nid;
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if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
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if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
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@ -5717,23 +5723,23 @@ static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
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if (src_nid == dst_nid)
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if (src_nid == dst_nid)
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return false;
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return false;
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if (numa_group) {
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/* Migrating away from the preferred node is bad. */
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/* Task is moving within/into the group's interleave set. */
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if (node_isset(dst_nid, numa_group->active_nodes))
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return false;
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/* Task is moving out of the group's interleave set. */
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if (node_isset(src_nid, numa_group->active_nodes))
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return true;
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return group_faults(p, dst_nid) < group_faults(p, src_nid);
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}
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/* Migrating away from the preferred node is always bad. */
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if (src_nid == p->numa_preferred_nid)
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if (src_nid == p->numa_preferred_nid)
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return true;
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return true;
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return task_faults(p, dst_nid) < task_faults(p, src_nid);
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/* Encourage migration to the preferred node. */
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if (dst_nid == p->numa_preferred_nid)
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return false;
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if (numa_group) {
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src_faults = group_faults(p, src_nid);
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dst_faults = group_faults(p, dst_nid);
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} else {
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src_faults = task_faults(p, src_nid);
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dst_faults = task_faults(p, dst_nid);
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}
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return dst_faults < src_faults;
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}
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}
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#else
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#else
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