linux-kernel - [PATCH v2 19/19] sched/numa: Move task_placement closer to numa_migrate

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Date:   Wed, 20 Jun 2018 22:33:00 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Rik van Riel <riel@...riel.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH v2 19/19] sched/numa: Move task_placement closer to numa_migrate_preferred

numa_migrate_preferred is called periodically or when task preferred
node changes. Preferred node evaluations happen once per scan sequence.

If the scan completion happens just after the periodic numa migration,
then we try to migrate to the preferred node and the preferred node might
change, needing another node migration.

Avoid this by checking for scan sequence completion only when checking
for periodic migration.

Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS  LAST_PATCH  WITH_PATCH  %CHANGE
16    25862.6     26158.1     1.14258
1     74357       72725       -2.19482

Running SPECjbb2005 on a 16 node machine and comparing bops/JVM
JVMS  LAST_PATCH  WITH_PATCH  %CHANGE
8     117019      113992      -2.58
1     179095      174947      -2.31

(numbers from v1 based on v4.17-rc5)
Testcase       Time:         Min         Max         Avg      StdDev
numa01.sh      Real:      449.46      770.77      615.22      101.70
numa01.sh       Sys:      132.72      208.17      170.46       24.96
numa01.sh      User:    39185.26    60290.89    50066.76     6807.84
numa02.sh      Real:       60.85       61.79       61.28        0.37
numa02.sh       Sys:       15.34       24.71       21.08        3.61
numa02.sh      User:     5204.41     5249.85     5231.21       17.60
numa03.sh      Real:      785.50      916.97      840.77       44.98
numa03.sh       Sys:      108.08      133.60      119.43        8.82
numa03.sh      User:    61422.86    70919.75    64720.87     3310.61
numa04.sh      Real:      429.57      587.37      480.80       57.40
numa04.sh       Sys:      240.61      321.97      290.84       33.58
numa04.sh      User:    34597.65    40498.99    37079.48     2060.72
numa05.sh      Real:      392.09      431.25      414.65       13.82
numa05.sh       Sys:      229.41      372.48      297.54       53.14
numa05.sh      User:    33390.86    34697.49    34222.43      556.42


Testcase       Time:         Min         Max         Avg      StdDev 	%Change
numa01.sh      Real:      424.63      566.18      498.12       59.26 	 23.50%
numa01.sh       Sys:      160.19      256.53      208.98       37.02 	 -18.4%
numa01.sh      User:    37320.00    46225.58    42001.57     3482.45 	 19.20%
numa02.sh      Real:       60.17       62.47       60.91        0.85 	 0.607%
numa02.sh       Sys:       15.30       22.82       17.04        2.90 	 23.70%
numa02.sh      User:     5202.13     5255.51     5219.08       20.14 	 0.232%
numa03.sh      Real:      823.91      844.89      833.86        8.46 	 0.828%
numa03.sh       Sys:      130.69      148.29      140.47        6.21 	 -14.9%
numa03.sh      User:    62519.15    64262.20    63613.38      620.05 	 1.740%
numa04.sh      Real:      515.30      603.74      548.56       30.93 	 -12.3%
numa04.sh       Sys:      459.73      525.48      489.18       21.63 	 -40.5%
numa04.sh      User:    40561.96    44919.18    42047.87     1526.85 	 -11.8%
numa05.sh      Real:      396.58      454.37      421.13       19.71 	 -1.53%
numa05.sh       Sys:      208.72      422.02      348.90       73.60 	 -14.7%
numa05.sh      User:    33124.08    36109.35    34846.47     1089.74 	 -1.79%

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
 kernel/sched/fair.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 36d1414..f29d59f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2182,9 +2182,6 @@ static void task_numa_placement(struct task_struct *p)
 		/* Set the new preferred node */
 		if (max_nid != p->numa_preferred_nid)
 			sched_setnuma(p, max_nid);
-
-		if (task_node(p) != p->numa_preferred_nid)
-			numa_migrate_preferred(p);
 	}
 
 	update_task_scan_period(p, fault_types[0], fault_types[1]);
@@ -2387,14 +2384,14 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
 				numa_is_active_node(mem_node, ng))
 		local = 1;
 
-	task_numa_placement(p);
-
 	/*
 	 * Retry task to preferred node migration periodically, in case it
 	 * case it previously failed, or the scheduler moved us.
 	 */
-	if (time_after(jiffies, p->numa_migrate_retry))
+	if (time_after(jiffies, p->numa_migrate_retry)) {
+		task_numa_placement(p);
 		numa_migrate_preferred(p);
+	}
 
 	if (migrated)
 		p->numa_pages_migrated += pages;
-- 
1.8.3.1