linux-kernel - [PATCH 54/63] sched: numa: fix task or group comparison

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1380288468-5551-55-git-send-email-mgorman@suse.de>
Date:	Fri, 27 Sep 2013 14:27:39 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Rik van Riel <riel@...hat.com>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 54/63] sched: numa: fix task or group comparison

From: Rik van Riel <riel@...hat.com>

This patch separately considers task and group affinities when
searching for swap candidates during NUMA placement. If tasks
are part of the same group, or no group at all, the task weights
are considered.

Some hysteresis is added to prevent tasks within one group from
getting bounced between NUMA nodes due to tiny differences.

If tasks are part of different groups, the code compares group
weights, in order to favor grouping task groups together.

The patch also changes the group weight multiplier to be the
same as the task weight multiplier, since the two are no longer
added up like before.

Signed-off-by: Rik van Riel <riel@...hat.com>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 kernel/sched/fair.c | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 60ca698..f232be6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -962,7 +962,7 @@ static inline unsigned long group_weight(struct task_struct *p, int nid)
 	if (!total_faults)
 		return 0;
 
-	return 1200 * group_faults(p, nid) / total_faults;
+	return 1000 * group_faults(p, nid) / total_faults;
 }
 
 static unsigned long weighted_cpuload(const int cpu);
@@ -1068,16 +1068,34 @@ static void task_numa_compare(struct task_numa_env *env,
 
 		/*
 		 * If dst and source tasks are in the same NUMA group, or not
-		 * in any group then look only at task weights otherwise give
-		 * priority to the group weights.
+		 * in any group then look only at task weights.
 		 */
-		if (!cur->numa_group || !env->p->numa_group ||
-		    cur->numa_group == env->p->numa_group) {
+		if (cur->numa_group == env->p->numa_group) {
 			imp = taskimp + task_weight(cur, env->src_nid) -
 			      task_weight(cur, env->dst_nid);
+			/*
+			 * Add some hysteresis to prevent swapping the
+			 * tasks within a group over tiny differences.
+			 */
+			if (cur->numa_group)
+				imp -= imp/16;
 		} else {
-			imp = groupimp + group_weight(cur, env->src_nid) -
-			       group_weight(cur, env->dst_nid);
+			/*
+			 * Compare the group weights. If a task is all by
+			 * itself (not part of a group), use the task weight
+			 * instead.
+			 */
+			if (env->p->numa_group)
+				imp = groupimp;
+			else
+				imp = taskimp;
+
+			if (cur->numa_group)
+				imp += group_weight(cur, env->src_nid) -
+				       group_weight(cur, env->dst_nid);
+			else
+				imp += task_weight(cur, env->src_nid) -
+				       task_weight(cur, env->dst_nid);
 		}
 	}
 
-- 
1.8.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/