linux-kernel - [PATCH 09/13] sched: Favour moving tasks towards nodes that incurred more faults

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: <1372861300-9973-10-git-send-email-mgorman@suse.de>
Date:	Wed,  3 Jul 2013 15:21:36 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	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 09/13] sched: Favour moving tasks towards nodes that incurred more faults

The scheduler already favours moving tasks towards its preferred node but
does nothing special if the destination node is anything else. This patch
favours moving tasks towards a destination node if more NUMA hinting faults
were recorded on it. Similarly if migrating to a destination node would
degrade locality based on NUMA hinting faults then it will be resisted.

Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 kernel/sched/fair.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 48 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e8d9b3e..e451859 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3967,22 +3967,54 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 }
 
 #ifdef CONFIG_NUMA_BALANCING
+
+static bool migrate_locality_prepare(struct task_struct *p, struct lb_env *env,
+				int *src_nid, int *dst_nid)
+{
+	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
+		return false;
+
+	*src_nid = cpu_to_node(env->src_cpu);
+	*dst_nid = cpu_to_node(env->dst_cpu);
+
+	if (*src_nid == *dst_nid ||
+	    p->numa_migrate_seq >= sysctl_numa_balancing_settle_count)
+		return false;
+
+	return true;
+}
+
 /* Returns true if the destination node has incurred more faults */
 static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
 {
 	int src_nid, dst_nid;
 
-	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
+	if (!migrate_locality_prepare(p, env, &src_nid, &dst_nid))
 		return false;
 
-	src_nid = cpu_to_node(env->src_cpu);
-	dst_nid = cpu_to_node(env->dst_cpu);
+	/* Move towards node if it is the preferred node */
+	if (p->numa_preferred_nid == dst_nid)
+		return true;
 
-	if (src_nid == dst_nid ||
-	    p->numa_migrate_seq >= sysctl_numa_balancing_settle_count)
+	/*
+	 * Move towards node if there were a higher number of private
+	 * NUMA hinting faults recorded on it
+	 */
+	if (p->numa_faults[task_faults_idx(dst_nid, 1)] >
+	    p->numa_faults[task_faults_idx(src_nid, 1)])
+		return true;
+
+	return false;
+}
+
+static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
+{
+	int src_nid, dst_nid;
+
+	if (!migrate_locality_prepare(p, env, &src_nid, &dst_nid))
 		return false;
 
-	if (p->numa_preferred_nid == dst_nid)
+	if (p->numa_faults[src_nid] > p->numa_faults[dst_nid])
 		return true;
 
 	return false;
@@ -3993,6 +4025,14 @@ static inline bool migrate_improves_locality(struct task_struct *p,
 {
 	return false;
 }
+
+
+static inline bool migrate_degrades_locality(struct task_struct *p,
+					     struct lb_env *env)
+{
+	return false;
+}
+
 #endif
 
 /*
@@ -4048,6 +4088,8 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
 	 * 3) too many balance attempts have failed.
 	 */
 	tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
+	if (!tsk_cache_hot)
+		tsk_cache_hot = migrate_degrades_locality(p, env);
 
 	if (migrate_improves_locality(p, env)) {
 #ifdef CONFIG_SCHEDSTATS
-- 
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/