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Date: Wed, 21 Nov 2012 10:21:52 +0000
From: Mel Gorman <mgorman@...e.de>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Andrea Arcangeli <aarcange@...hat.com>,
Ingo Molnar <mingo@...nel.org>
Cc: Rik van Riel <riel@...hat.com>,
Johannes Weiner <hannes@...xchg.org>,
Hugh Dickins <hughd@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Paul Turner <pjt@...gle.com>,
Lee Schermerhorn <Lee.Schermerhorn@...com>,
Alex Shi <lkml.alex@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 46/46] Simple CPU follow
---
kernel/sched/fair.c | 112 +++++++--------------------------------------------
1 file changed, 15 insertions(+), 97 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5cc5b60..fd53f17 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -877,118 +877,36 @@ static inline unsigned long balancenuma_mm_weight(struct task_struct *p,
*/
static void task_numa_find_placement(struct task_struct *p)
{
- struct cpumask *allowed = tsk_cpus_allowed(p);
- int this_cpu = smp_processor_id();
int this_nid = numa_node_id();
long p_task_weight, p_mm_weight;
- long weight_diff_max = 0;
- struct task_struct *selected_task = NULL;
+ long max_weight = 0;
int selected_nid = -1;
int nid;
p_task_weight = balancenuma_task_weight(p, this_nid);
p_mm_weight = balancenuma_mm_weight(p, this_nid);
- /* Examine a task on every other node */
+ /* Check if this task should run on another node */
for_each_online_node(nid) {
- int cpu;
- for_each_cpu_and(cpu, cpumask_of_node(nid), allowed) {
- struct rq *rq;
- struct mm_struct *other_mm;
- struct task_struct *other_task;
- long this_weight, other_weight, p_weight;
- long other_diff, this_diff;
-
- if (!cpu_online(cpu))
- continue;
-
- /* Idle CPU, consider running this task on that node */
- if (idle_cpu(cpu)) {
- this_weight = balancenuma_task_weight(p, nid);
- other_weight = 0;
- other_task = NULL;
- p_weight = p_task_weight;
- goto compare_other;
- }
-
- /* Racy check if a task is running on the other rq */
- rq = cpu_rq(cpu);
- other_mm = rq->curr->mm;
- if (!other_mm || !other_mm->mm_balancenuma)
- continue;
-
- /* Effectively pin the other task to get fault stats */
- raw_spin_lock_irq(&rq->lock);
- other_task = rq->curr;
- other_mm = other_task->mm;
-
- /* Ensure the other task has usable stats */
- if (!other_task->task_balancenuma ||
- !other_task->task_balancenuma->task_numa_fault_tot ||
- !other_mm ||
- !other_mm->mm_balancenuma ||
- !other_mm->mm_balancenuma->mm_numa_fault_tot) {
- raw_spin_unlock_irq(&rq->lock);
- continue;
- }
-
- /*
- * Read the fault statistics. If the remote task is a
- * thread in the process then use the task statistics.
- * Otherwise use the per-mm statistics.
- */
- if (other_mm == p->mm) {
- this_weight = balancenuma_task_weight(p, nid);
- other_weight = balancenuma_task_weight(other_task, nid);
- p_weight = p_task_weight;
- } else {
- this_weight = balancenuma_mm_weight(p, nid);
- other_weight = balancenuma_mm_weight(other_task, nid);
- p_weight = p_mm_weight;
- }
-
- raw_spin_unlock_irq(&rq->lock);
-
-compare_other:
- /*
- * other_diff: How much does the current task perfer to
- * run on the remote node thn the task that is
- * currently running there?
- */
- other_diff = this_weight - other_weight;
+ unsigned long nid_weight;
- /*
- * this_diff: How much does the currrent task prefer to
- * run on the remote NUMA node compared to the current
- * node?
- */
- this_diff = this_weight - p_weight;
-
- /*
- * Would nid reduce the overall cross-node NUMA faults?
- */
- if (other_diff > 0 && this_diff > 0) {
- long weight_diff = other_diff + this_diff;
-
- /* Remember the best candidate. */
- if (weight_diff > weight_diff_max) {
- weight_diff_max = weight_diff;
- selected_nid = nid;
- selected_task = other_task;
- }
- }
+ /*
+ * Read the fault statistics. If the remote task is a
+ * thread in the process then use the task statistics.
+ * Otherwise use the per-mm statistics.
+ */
+ nid_weight = balancenuma_task_weight(p, nid) +
+ balancenuma_mm_weight(p, nid);
- /*
- * Examine just one task per node. Examing all tasks
- * disrupts the system excessively
- */
- break;
+ /* Remember the best candidate. */
+ if (nid_weight > max_weight) {
+ max_weight = nid_weight;
+ selected_nid = nid;
}
}
- if (selected_nid != -1 && selected_nid != this_nid) {
+ if (selected_nid != -1 && selected_nid != this_nid)
sched_setnode(p, selected_nid);
- }
}
static void task_numa_placement(struct task_struct *p)
--
1.7.9.2
--
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