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Commit 688b7585 authored by Mel Gorman's avatar Mel Gorman Committed by Ingo Molnar
Browse files

sched/numa: Select a preferred node with the most numa hinting faults 



This patch selects a preferred node for a task to run on based on the
NUMA hinting faults. This information is later used to migrate tasks
towards the node during balancing.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-21-git-send-email-mgorman@suse.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f809ca9a

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1344,6 +1344,7 @@ struct task_struct { 
	struct callback_head numa_work;



	unsigned long *numa_faults;

	int numa_preferred_nid;

#endif /* CONFIG_NUMA_BALANCING */



	struct rcu_head rcu;

kernel/sched/core.c

+1 −0
Original line number Diff line number Diff line
@@ -1633,6 +1633,7 @@ static void __sched_fork(struct task_struct *p) 
	p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;

	p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0;

	p->numa_scan_period = sysctl_numa_balancing_scan_delay;

	p->numa_preferred_nid = -1;

	p->numa_work.next = &p->numa_work;

	p->numa_faults = NULL;

#endif /* CONFIG_NUMA_BALANCING */

kernel/sched/fair.c

+15 −2
Original line number Diff line number Diff line
@@ -879,7 +879,8 @@ static unsigned int task_scan_max(struct task_struct *p) 


static void task_numa_placement(struct task_struct *p)

{

	int seq;

	int seq, nid, max_nid = -1;

	unsigned long max_faults = 0;



	if (!p->mm)	/* for example, ksmd faulting in a user's mm */

		return;
@@ -889,7 +890,19 @@ static void task_numa_placement(struct task_struct *p) 
	p->numa_scan_seq = seq;

	p->numa_scan_period_max = task_scan_max(p);



	/* FIXME: Scheduling placement policy hints go here */

	/* Find the node with the highest number of faults */

	for_each_online_node(nid) {

		unsigned long faults = p->numa_faults[nid];

		p->numa_faults[nid] >>= 1;

		if (faults > max_faults) {

			max_faults = faults;

			max_nid = nid;

		}

	}



	/* Update the tasks preferred node if necessary */

	if (max_faults && max_nid != p->numa_preferred_nid)

		p->numa_preferred_nid = max_nid;

}



/*