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Subject[PATCH 19/63] sched: Track NUMA hinting faults on per-node basis
Date
This patch tracks what nodes numa hinting faults were incurred on.
This information is later used to schedule a task on the node storing
the pages most frequently faulted by the task.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/sched.h | 2 ++
kernel/sched/core.c | 3 +++
kernel/sched/fair.c | 11 ++++++++++-
kernel/sched/sched.h | 12 ++++++++++++
4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 49b426e..dfba435 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1334,6 +1334,8 @@ struct task_struct {
unsigned int numa_scan_period_max;
u64 node_stamp; /* migration stamp */
struct callback_head numa_work;
+
+ unsigned long *numa_faults;
#endif /* CONFIG_NUMA_BALANCING */

struct rcu_head rcu;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9d7a33a..dbc2de6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1644,6 +1644,7 @@ static void __sched_fork(struct task_struct *p)
p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0;
p->numa_scan_period = sysctl_numa_balancing_scan_delay;
p->numa_work.next = &p->numa_work;
+ p->numa_faults = NULL;
#endif /* CONFIG_NUMA_BALANCING */
}

@@ -1905,6 +1906,8 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
if (mm)
mmdrop(mm);
if (unlikely(prev_state == TASK_DEAD)) {
+ task_numa_free(prev);
+
/*
* Remove function-return probe instances associated with this
* task and put them back on the free list.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cdd656c..55ec7ad 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -902,7 +902,14 @@ void task_numa_fault(int node, int pages, bool migrated)
if (!numabalancing_enabled)
return;

- /* FIXME: Allocate task-specific structure for placement policy here */
+ /* Allocate buffer to track faults on a per-node basis */
+ if (unlikely(!p->numa_faults)) {
+ int size = sizeof(*p->numa_faults) * nr_node_ids;
+
+ p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
+ if (!p->numa_faults)
+ return;
+ }

/*
* If pages are properly placed (did not migrate) then scan slower.
@@ -918,6 +925,8 @@ void task_numa_fault(int node, int pages, bool migrated)
}

task_numa_placement(p);
+
+ p->numa_faults[node] += pages;
}

static void reset_ptenuma_scan(struct task_struct *p)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 7c17661..46c2068 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -6,6 +6,7 @@
#include <linux/spinlock.h>
#include <linux/stop_machine.h>
#include <linux/tick.h>
+#include <linux/slab.h>

#include "cpupri.h"
#include "cpuacct.h"
@@ -553,6 +554,17 @@ static inline u64 rq_clock_task(struct rq *rq)
return rq->clock_task;
}

+#ifdef CONFIG_NUMA_BALANCING
+static inline void task_numa_free(struct task_struct *p)
+{
+ kfree(p->numa_faults);
+}
+#else /* CONFIG_NUMA_BALANCING */
+static inline void task_numa_free(struct task_struct *p)
+{
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
#ifdef CONFIG_SMP

#define rcu_dereference_check_sched_domain(p) \
--
1.8.1.4


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