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Subject[RFC][PATCH 25/26] sched, numa: Only migrate long-running entities
It doesn't make much sense to memory migrate short running things.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/sched/numa.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
--- a/kernel/sched/numa.c
+++ b/kernel/sched/numa.c
@@ -15,6 +15,8 @@ struct numa_ops {
void (*mem_migrate)(struct numa_entity *ne, int node);
void (*cpu_migrate)(struct numa_entity *ne, int node);

+ u64 (*cpu_runtime)(struct numa_entity *ne);
+
bool (*tryget)(struct numa_entity *ne);
void (*put)(struct numa_entity *ne);
};
@@ -196,6 +198,21 @@ static void process_mem_migrate(struct n
lazy_migrate_process(ne_mm(ne), node);
}

+static u64 process_cpu_runtime(struct numa_entity *ne)
+{
+ struct task_struct *p, *t;
+ u64 runtime = 0;
+
+ rcu_read_lock();
+ t = p = ne_owner(ne);
+ if (p) do {
+ runtime += t->se.sum_exec_runtime; // @#$#@ 32bit
+ } while ((t = next_thread(t)) != p);
+ rcu_read_unlock();
+
+ return runtime;
+}
+
static bool process_tryget(struct numa_entity *ne)
{
/*
@@ -219,6 +236,8 @@ static const struct numa_ops process_num
.mem_migrate = process_mem_migrate,
.cpu_migrate = process_cpu_migrate,

+ .cpu_runtime = process_cpu_runtime,
+
.tryget = process_tryget,
.put = process_put,
};
@@ -616,6 +635,14 @@ static bool can_move_ne(struct numa_enti
* XXX: consider mems_allowed, stinking cpusets has mems_allowed
* per task and it can actually differ over a whole process, la-la-la.
*/
+
+ /*
+ * Don't bother migrating memory if there's less than 1 second
+ * of runtime on the tasks.
+ */
+ if (ne->nops->cpu_runtime(ne) < NSEC_PER_SEC)
+ return false;
+
return true;
}

@@ -1000,6 +1027,20 @@ static void numa_group_cpu_migrate(struc
rcu_read_unlock();
}

+static u64 numa_group_cpu_runtime(struct numa_entity *ne)
+{
+ struct numa_group *ng = ne_ng(ne);
+ struct task_struct *p;
+ u64 runtime = 0;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(p, &ng->tasks, ng_entry)
+ runtime += p->se.sum_exec_runtime; // @#$# 32bit
+ rcu_read_unlock();
+
+ return runtime;
+}
+
static bool numa_group_tryget(struct numa_entity *ne)
{
/*
@@ -1020,6 +1061,8 @@ static const struct numa_ops numa_group_
.mem_migrate = numa_group_mem_migrate,
.cpu_migrate = numa_group_cpu_migrate,

+ .cpu_runtime = numa_group_cpu_runtime,
+
.tryget = numa_group_tryget,
.put = numa_group_put,
};



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