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

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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: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik 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: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-21-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mel Gorman 2013-10-07 11:28:58 +01:00 committed by Ingo Molnar
parent f809ca9a55
commit 688b7585d1
3 changed files with 17 additions and 2 deletions
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1
include/linux/sched.h
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@ -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;

1
kernel/sched/core.c
View file

@ -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 */

17
kernel/sched/fair.c
View file

@ -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;
}
/*