summaryrefslogtreecommitdiff
path: root/kernel/sched
diff options
context:
space:
mode:
authorMel Gorman <mgorman@suse.de>2013-10-07 11:29:18 +0100
committerIngo Molnar <mingo@kernel.org>2013-10-09 14:47:41 +0200
commit2c8a50aa873a7e1d6cc0913362051ff9912dc6ca (patch)
treeca32297c046a3789b44e1255b94ef8d0b760d1f9 /kernel/sched
parentfb13c7ee0ed387bd6bec4b4024a4d49b1bd504f1 (diff)
sched/numa: Favor placing a task on the preferred node
A tasks preferred node is selected based on the number of faults recorded for a node but the actual task_numa_migate() conducts a global search regardless of the preferred nid. This patch checks if the preferred nid has capacity and if so, searches for a CPU within that node. This avoids a global search when the preferred node is not overloaded. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-41-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c54
1 files changed, 35 insertions, 19 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1422765d4b86..09aac90df89e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1052,6 +1052,20 @@ unlock:
rcu_read_unlock();
}
+static void task_numa_find_cpu(struct task_numa_env *env, long imp)
+{
+ int cpu;
+
+ for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
+ /* Skip this CPU if the source task cannot migrate */
+ if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p)))
+ continue;
+
+ env->dst_cpu = cpu;
+ task_numa_compare(env, imp);
+ }
+}
+
static int task_numa_migrate(struct task_struct *p)
{
struct task_numa_env env = {
@@ -1068,7 +1082,8 @@ static int task_numa_migrate(struct task_struct *p)
};
struct sched_domain *sd;
unsigned long faults;
- int nid, cpu, ret;
+ int nid, ret;
+ long imp;
/*
* Pick the lowest SD_NUMA domain, as that would have the smallest
@@ -1085,28 +1100,29 @@ static int task_numa_migrate(struct task_struct *p)
faults = task_faults(p, env.src_nid);
update_numa_stats(&env.src_stats, env.src_nid);
+ env.dst_nid = p->numa_preferred_nid;
+ imp = task_faults(env.p, env.dst_nid) - faults;
+ update_numa_stats(&env.dst_stats, env.dst_nid);
- /* Find an alternative node with relatively better statistics */
- for_each_online_node(nid) {
- long imp;
-
- if (nid == env.src_nid)
- continue;
-
- /* Only consider nodes that recorded more faults */
- imp = task_faults(p, nid) - faults;
- if (imp < 0)
- continue;
+ /*
+ * If the preferred nid has capacity then use it. Otherwise find an
+ * alternative node with relatively better statistics.
+ */
+ if (env.dst_stats.has_capacity) {
+ task_numa_find_cpu(&env, imp);
+ } else {
+ for_each_online_node(nid) {
+ if (nid == env.src_nid || nid == p->numa_preferred_nid)
+ continue;
- env.dst_nid = nid;
- update_numa_stats(&env.dst_stats, env.dst_nid);
- for_each_cpu(cpu, cpumask_of_node(nid)) {
- /* Skip this CPU if the source task cannot migrate */
- if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
+ /* Only consider nodes that recorded more faults */
+ imp = task_faults(env.p, nid) - faults;
+ if (imp < 0)
continue;
- env.dst_cpu = cpu;
- task_numa_compare(&env, imp);
+ env.dst_nid = nid;
+ update_numa_stats(&env.dst_stats, env.dst_nid);
+ task_numa_find_cpu(&env, imp);
}
}