Re: [PATCH 19/63] sched: Track NUMA hinting faults on per-node basis

From: Wanpeng Li <liwanp@linux.vnet.ibm.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Rik van Riel <riel@redhat.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 19/63] sched: Track NUMA hinting faults on per-node basis
Date: Wed, 4 Dec 2013 13:37:04 +0800	[thread overview]
Message-ID: <529ebf88.28e9440a.54f2.fffff6aaSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <529ebe8c.a19e420a.72bb.ffff9a55SMTPIN_ADDED_BROKEN@mx.google.com>

On Wed, Dec 04, 2013 at 01:32:42PM +0800, Wanpeng Li wrote:
>On Mon, Oct 07, 2013 at 11:28:57AM +0100, Mel Gorman wrote:
>>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 a8095ad..8828e40 100644
>>--- a/include/linux/sched.h
>>+++ b/include/linux/sched.h
>>@@ -1332,6 +1332,8 @@ 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 681945e..aad2e02 100644
>>--- a/kernel/sched/core.c
>>+++ b/kernel/sched/core.c
>>@@ -1629,6 +1629,7 @@ 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 */
>>
>> 	cpu_hotplug_init_task(p);
>>@@ -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);
>
>Function task_numa_free() depends on patch 43/64.

Sorry, I miss it.

>
>Regards,
>Wanpeng Li 
>
>>+
>> 		/*
>> 		 * 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 8cea7a2..df300d9 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 b3c5653..6a955f4 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"
>>@@ -552,6 +553,17 @@ 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) \
>>-- 
>>1.8.4
>>
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