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From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Rik van Riel <riel@surriel.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 09/19] sched/numa: Modify migrate_swap to accept additional params
Date: Mon,  4 Jun 2018 15:30:18 +0530	[thread overview]
Message-ID: <1528106428-19992-10-git-send-email-srikar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1528106428-19992-1-git-send-email-srikar@linux.vnet.ibm.com>

There are checks in migrate_swap_stop that check if the task/cpu
combination is as per migrate_swap_arg before migrating.

However atleast one of the two tasks to be swapped by migrate_swap could
have migrated to a completely different cpu before updating the
migrate_swap_arg. The new cpu where the task is currently running could
be a different node too. If the task has migrated, numa balancer might
end up placing a task in a wrong node.  Instead of achieving node
consolidation, it may end up spreading the load across nodes.

To avoid that pass the cpus as additional parameters.

While here, place migrate_swap under CONFIG_NUMA_BALANCING.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
 kernel/sched/core.c  | 9 ++++++---
 kernel/sched/fair.c  | 3 ++-
 kernel/sched/sched.h | 3 ++-
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 092f7c4..68849c2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1178,6 +1178,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 	__set_task_cpu(p, new_cpu);
 }
 
+#ifdef CONFIG_NUMA_BALANCING
 static void __migrate_swap_task(struct task_struct *p, int cpu)
 {
 	if (task_on_rq_queued(p)) {
@@ -1259,16 +1260,17 @@ static int migrate_swap_stop(void *data)
 /*
  * Cross migrate two tasks
  */
-int migrate_swap(struct task_struct *cur, struct task_struct *p)
+int migrate_swap(struct task_struct *cur, struct task_struct *p,
+		int target_cpu, int curr_cpu)
 {
 	struct migration_swap_arg arg;
 	int ret = -EINVAL;
 
 	arg = (struct migration_swap_arg){
 		.src_task = cur,
-		.src_cpu = task_cpu(cur),
+		.src_cpu = curr_cpu,
 		.dst_task = p,
-		.dst_cpu = task_cpu(p),
+		.dst_cpu = target_cpu,
 	};
 
 	if (arg.src_cpu == arg.dst_cpu)
@@ -1293,6 +1295,7 @@ int migrate_swap(struct task_struct *cur, struct task_struct *p)
 out:
 	return ret;
 }
+#endif /* CONFIG_NUMA_BALANCING */
 
 /*
  * wait_task_inactive - wait for a thread to unschedule.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 35c4a75..46d773c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1810,7 +1810,8 @@ static int task_numa_migrate(struct task_struct *p)
 		return ret;
 	}
 
-	ret = migrate_swap(p, env.best_task);
+	ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu);
+
 	if (ret != 0)
 		trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
 	put_task_struct(env.best_task);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 15750c2..211841e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1068,7 +1068,8 @@ enum numa_faults_stats {
 };
 extern void sched_setnuma(struct task_struct *p, int node);
 extern int migrate_task_to(struct task_struct *p, int cpu);
-extern int migrate_swap(struct task_struct *, struct task_struct *);
+extern int migrate_swap(struct task_struct *p, struct task_struct *t,
+			int cpu, int scpu);
 #endif /* CONFIG_NUMA_BALANCING */
 
 #ifdef CONFIG_SMP
-- 
1.8.3.1

  parent reply	other threads:[~2018-06-04 10:01 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-04 10:00 [PATCH 00/19] Fixes for sched/numa_balancing Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 01/19] sched/numa: Remove redundant field Srikar Dronamraju
2018-06-04 14:53   ` Rik van Riel
2018-06-05  8:41   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 02/19] sched/numa: Evaluate move once per node Srikar Dronamraju
2018-06-04 14:51   ` Rik van Riel
2018-06-04 15:45     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 03/19] sched/numa: Simplify load_too_imbalanced Srikar Dronamraju
2018-06-04 14:57   ` Rik van Riel
2018-06-05  8:46   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 04/19] sched/numa: Set preferred_node based on best_cpu Srikar Dronamraju
2018-06-04 12:18   ` Peter Zijlstra
2018-06-04 12:53     ` Srikar Dronamraju
2018-06-04 12:23   ` Peter Zijlstra
2018-06-04 12:59     ` Srikar Dronamraju
2018-06-04 13:39       ` Peter Zijlstra
2018-06-04 13:48         ` Srikar Dronamraju
2018-06-04 14:37       ` Rik van Riel
2018-06-04 15:56         ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 05/19] sched/numa: Use task faults only if numa_group is not yet setup Srikar Dronamraju
2018-06-04 12:24   ` Peter Zijlstra
2018-06-04 13:09     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 06/19] sched/debug: Reverse the order of printing faults Srikar Dronamraju
2018-06-04 16:28   ` Rik van Riel
2018-06-05  8:50   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 07/19] sched/numa: Skip nodes that are at hoplimit Srikar Dronamraju
2018-06-04 16:27   ` Rik van Riel
2018-06-05  8:50   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 08/19] sched/numa: Remove unused task_capacity from numa_stats Srikar Dronamraju
2018-06-04 16:28   ` Rik van Riel
2018-06-05  8:57   ` Mel Gorman
2018-06-04 10:00 ` Srikar Dronamraju [this message]
2018-06-04 17:00   ` [PATCH 09/19] sched/numa: Modify migrate_swap to accept additional params Rik van Riel
2018-06-05  8:58   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 10/19] sched/numa: Stop multiple tasks from moving to the cpu at the same time Srikar Dronamraju
2018-06-04 17:57   ` Rik van Riel
2018-06-05  9:51   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 11/19] sched/numa: Restrict migrating in parallel to the same node Srikar Dronamraju
2018-06-04 17:59   ` Rik van Riel
2018-06-05  9:53   ` Mel Gorman
2018-06-06 12:58     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 12/19] sched:numa Remove numa_has_capacity Srikar Dronamraju
2018-06-04 18:07   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 13/19] mm/migrate: Use xchg instead of spinlock Srikar Dronamraju
2018-06-04 18:22   ` Rik van Riel
2018-06-04 19:28   ` Peter Zijlstra
2018-06-05  7:24     ` Srikar Dronamraju
2018-06-05  8:16       ` Peter Zijlstra
2018-06-04 10:00 ` [PATCH 14/19] sched/numa: Updation of scan period need not be in lock Srikar Dronamraju
2018-06-04 18:24   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 15/19] sched/numa: Use group_weights to identify if migration degrades locality Srikar Dronamraju
2018-06-04 18:56   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 16/19] sched/numa: Detect if node actively handling migration Srikar Dronamraju
2018-06-04 20:05   ` Rik van Riel
2018-06-05  3:56     ` Srikar Dronamraju
2018-06-05 13:07       ` Rik van Riel
2018-06-06 12:55         ` Srikar Dronamraju
2018-06-06 13:55           ` Rik van Riel
2018-06-06 15:32             ` Srikar Dronamraju
2018-06-06 17:06               ` Rik van Riel
2018-06-04 10:00 ` [PATCH 17/19] sched/numa: Pass destination cpu as a parameter to migrate_task_rq Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 18/19] sched/numa: Reset scan rate whenever task moves across nodes Srikar Dronamraju
2018-06-04 20:08   ` Rik van Riel
2018-06-05  9:58   ` Mel Gorman
2018-06-06 13:47     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 19/19] sched/numa: Move task_placement closer to numa_migrate_preferred Srikar Dronamraju

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