sched/numa: Track NUMA hinting faults on per-node basis

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>
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/1381141781-10992-20-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index fdcb4c8..a810e95 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1342,6 +1342,8 @@ 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 aee7e4d..6808d35 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1634,6 +1634,7 @@ 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 */
 }
 
@@ -1892,6 +1893,8 @@ 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 c6c3302..0bb3e0a 100644 (file)
--- 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 e82484d..199099c 100644 (file)
--- 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"
@@ -555,6 +556,17 @@ 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) \