linux-kernel - [PATCH v2 14/19] sched/numa: Updation of scan period need not be in lock

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Date:   Wed, 20 Jun 2018 22:32:55 +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 14/19] sched/numa: Updation of scan period need not be in lock

The metrics for updating scan periods are local or task specific.
Currently this updation happens under numa_group lock which seems
unnecessary. Hence move this updation outside the lock.

Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS  LAST_PATCH  WITH_PATCH  %CHANGE
16    25355.9     25645.4     1.141
1     72812       72142       -0.92

Reviewed-by: Rik van Riel <riel@...riel.com>
Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
 kernel/sched/fair.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 10b6886..711b533 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2162,8 +2162,6 @@ static void task_numa_placement(struct task_struct *p)
 		}
 	}
 
-	update_task_scan_period(p, fault_types[0], fault_types[1]);
-
 	if (p->numa_group) {
 		numa_group_count_active_nodes(p->numa_group);
 		spin_unlock_irq(group_lock);
@@ -2178,6 +2176,8 @@ static void task_numa_placement(struct task_struct *p)
 		if (task_node(p) != p->numa_preferred_nid)
 			numa_migrate_preferred(p);
 	}
+
+	update_task_scan_period(p, fault_types[0], fault_types[1]);
 }
 
 static inline int get_numa_group(struct numa_group *grp)
-- 
1.8.3.1