[tip:sched/core] sched/numa: Initialise numa_next_scan properly

[tip-bot for Mel Gorman]

Commit-ID:  7e8d16b6cbccb2f5da579f5085479fb82ba851b8
Gitweb:     http://git.kernel.org/tip/7e8d16b6cbccb2f5da579f5085479fb82ba851b8
Author:     Mel Gorman <mgorman@xxxxxxx>
AuthorDate: Mon, 7 Oct 2013 11:28:54 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 9 Oct 2013 12:40:19 +0200

sched/numa: Initialise numa_next_scan properly

Scan delay logic and resets are currently initialised to start scanning
immediately instead of delaying properly. Initialise them properly at
fork time and catch when a new mm has been allocated.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1381141781-10992-17-git-send-email-mgorman@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/sched/core.c | 4 ++--
 kernel/sched/fair.c | 7 +++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f575d5b..aee7e4d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1624,8 +1624,8 @@ static void __sched_fork(struct task_struct *p)
 
 #ifdef CONFIG_NUMA_BALANCING
 	if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
-		p->mm->numa_next_scan = jiffies;
-		p->mm->numa_next_reset = jiffies;
+		p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
+		p->mm->numa_next_reset = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
 		p->mm->numa_scan_seq = 0;
 	}
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 49b11fa..0966f0c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -900,6 +900,13 @@ void task_numa_work(struct callback_head *work)
 	if (p->flags & PF_EXITING)
 		return;
 
+	if (!mm->numa_next_reset || !mm->numa_next_scan) {
+		mm->numa_next_scan = now +
+			msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
+		mm->numa_next_reset = now +
+			msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
+	}
+
 	/*
 	 * Reset the scan period if enough time has gone by. Objective is that
 	 * scanning will be reduced if pages are properly placed. As tasks
--
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