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Date: Thu, 10 Aug 2017 05:07:53 -0700
From: tip-bot for Rik van Riel <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: mgorman@...e.de, tglx@...utronix.de, torvalds@...ux-foundation.org,
hpa@...or.com, mingo@...nel.org, peterz@...radead.org,
linux-kernel@...r.kernel.org, riel@...hat.com
Subject: [tip:sched/core] sched/numa: Scale scan period with tasks in group
and shared/private
Commit-ID: b5dd77c8bdada7b6262d0cba02a6ed525bf4e6e1
Gitweb: http://git.kernel.org/tip/b5dd77c8bdada7b6262d0cba02a6ed525bf4e6e1
Author: Rik van Riel <riel@...hat.com>
AuthorDate: Mon, 31 Jul 2017 15:28:47 -0400
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 10 Aug 2017 12:18:16 +0200
sched/numa: Scale scan period with tasks in group and shared/private
Running 80 tasks in the same group, or as threads of the same process,
results in the memory getting scanned 80x as fast as it would be if a
single task was using the memory.
This really hurts some workloads.
Scale the scan period by the number of tasks in the numa group, and
the shared / private ratio, so the average rate at which memory in
the group is scanned corresponds roughly to the rate at which a single
task would scan its memory.
Signed-off-by: Rik van Riel <riel@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Mel Gorman <mgorman@...e.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: jhladky@...hat.com
Cc: lvenanci@...hat.com
Link: http://lkml.kernel.org/r/20170731192847.23050-3-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
kernel/sched/fair.c | 111 ++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 86 insertions(+), 25 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cb6b7c8..a7f1c3b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1071,6 +1071,29 @@ unsigned int sysctl_numa_balancing_scan_size = 256;
/* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
unsigned int sysctl_numa_balancing_scan_delay = 1000;
+struct numa_group {
+ atomic_t refcount;
+
+ spinlock_t lock; /* nr_tasks, tasks */
+ int nr_tasks;
+ pid_t gid;
+ int active_nodes;
+
+ struct rcu_head rcu;
+ unsigned long total_faults;
+ unsigned long max_faults_cpu;
+ /*
+ * Faults_cpu is used to decide whether memory should move
+ * towards the CPU. As a consequence, these stats are weighted
+ * more by CPU use than by memory faults.
+ */
+ unsigned long *faults_cpu;
+ unsigned long faults[0];
+};
+
+static inline unsigned long group_faults_priv(struct numa_group *ng);
+static inline unsigned long group_faults_shared(struct numa_group *ng);
+
static unsigned int task_nr_scan_windows(struct task_struct *p)
{
unsigned long rss = 0;
@@ -1107,13 +1130,47 @@ static unsigned int task_scan_min(struct task_struct *p)
return max_t(unsigned int, floor, scan);
}
+static unsigned int task_scan_start(struct task_struct *p)
+{
+ unsigned long smin = task_scan_min(p);
+ unsigned long period = smin;
+
+ /* Scale the maximum scan period with the amount of shared memory. */
+ if (p->numa_group) {
+ struct numa_group *ng = p->numa_group;
+ unsigned long shared = group_faults_shared(ng);
+ unsigned long private = group_faults_priv(ng);
+
+ period *= atomic_read(&ng->refcount);
+ period *= shared + 1;
+ period /= private + shared + 1;
+ }
+
+ return max(smin, period);
+}
+
static unsigned int task_scan_max(struct task_struct *p)
{
- unsigned int smin = task_scan_min(p);
- unsigned int smax;
+ unsigned long smin = task_scan_min(p);
+ unsigned long smax;
/* Watch for min being lower than max due to floor calculations */
smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
+
+ /* Scale the maximum scan period with the amount of shared memory. */
+ if (p->numa_group) {
+ struct numa_group *ng = p->numa_group;
+ unsigned long shared = group_faults_shared(ng);
+ unsigned long private = group_faults_priv(ng);
+ unsigned long period = smax;
+
+ period *= atomic_read(&ng->refcount);
+ period *= shared + 1;
+ period /= private + shared + 1;
+
+ smax = max(smax, period);
+ }
+
return max(smin, smax);
}
@@ -1129,26 +1186,6 @@ static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p));
}
-struct numa_group {
- atomic_t refcount;
-
- spinlock_t lock; /* nr_tasks, tasks */
- int nr_tasks;
- pid_t gid;
- int active_nodes;
-
- struct rcu_head rcu;
- unsigned long total_faults;
- unsigned long max_faults_cpu;
- /*
- * Faults_cpu is used to decide whether memory should move
- * towards the CPU. As a consequence, these stats are weighted
- * more by CPU use than by memory faults.
- */
- unsigned long *faults_cpu;
- unsigned long faults[0];
-};
-
/* Shared or private faults. */
#define NR_NUMA_HINT_FAULT_TYPES 2
@@ -1198,6 +1235,30 @@ static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)];
}
+static inline unsigned long group_faults_priv(struct numa_group *ng)
+{
+ unsigned long faults = 0;
+ int node;
+
+ for_each_online_node(node) {
+ faults += ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
+ }
+
+ return faults;
+}
+
+static inline unsigned long group_faults_shared(struct numa_group *ng)
+{
+ unsigned long faults = 0;
+ int node;
+
+ for_each_online_node(node) {
+ faults += ng->faults[task_faults_idx(NUMA_MEM, node, 0)];
+ }
+
+ return faults;
+}
+
/*
* A node triggering more than 1/3 as many NUMA faults as the maximum is
* considered part of a numa group's pseudo-interleaving set. Migrations
@@ -1808,7 +1869,7 @@ static int task_numa_migrate(struct task_struct *p)
* Reset the scan period if the task is being rescheduled on an
* alternative node to recheck if the tasks is now properly placed.
*/
- p->numa_scan_period = task_scan_min(p);
+ p->numa_scan_period = task_scan_start(p);
if (env.best_task == NULL) {
ret = migrate_task_to(p, env.best_cpu);
@@ -2459,7 +2520,7 @@ void task_numa_work(struct callback_head *work)
if (p->numa_scan_period == 0) {
p->numa_scan_period_max = task_scan_max(p);
- p->numa_scan_period = task_scan_min(p);
+ p->numa_scan_period = task_scan_start(p);
}
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
@@ -2587,7 +2648,7 @@ void task_tick_numa(struct rq *rq, struct task_struct *curr)
if (now > curr->node_stamp + period) {
if (!curr->node_stamp)
- curr->numa_scan_period = task_scan_min(curr);
+ curr->numa_scan_period = task_scan_start(curr);
curr->node_stamp += period;
if (!time_before(jiffies, curr->mm->numa_next_scan)) {
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