linux-kernel - [PATCH v2 4/5] mm: use node_page_state

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Date:   Tue, 19 Dec 2017 14:39:25 +0800
From:   Kemi Wang <kemi.wang@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Johannes Weiner <hannes@...xchg.org>,
        Christopher Lameter <cl@...ux.com>,
        YASUAKI ISHIMATSU <yasu.isimatu@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Nikolay Borisov <nborisov@...e.com>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        David Rientjes <rientjes@...gle.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Dave <dave.hansen@...ux.intel.com>,
        Andi Kleen <andi.kleen@...el.com>,
        Tim Chen <tim.c.chen@...el.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Ying Huang <ying.huang@...el.com>,
        Aaron Lu <aaron.lu@...el.com>, Aubrey Li <aubrey.li@...el.com>,
        Kemi Wang <kemi.wang@...el.com>, Linux MM <linux-mm@...ck.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 4/5] mm: use node_page_state_snapshot to avoid deviation

To avoid deviation, this patch uses node_page_state_snapshot instead of
node_page_state for node page stats query.
e.g. cat /proc/zoneinfo
     cat /sys/devices/system/node/node*/vmstat
     cat /sys/devices/system/node/node*/numastat

As it is a slow path and would not be read frequently, I would worry about
it.

Signed-off-by: Kemi Wang <kemi.wang@...el.com>
---
 drivers/base/node.c | 17 ++++++++++-------
 mm/vmstat.c         |  2 +-
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index a045ea1..cf303f8 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -169,12 +169,15 @@ static ssize_t node_read_numastat(struct device *dev,
 		       "interleave_hit %lu\n"
 		       "local_node %lu\n"
 		       "other_node %lu\n",
-		       node_page_state(NODE_DATA(dev->id), NUMA_HIT),
-		       node_page_state(NODE_DATA(dev->id), NUMA_MISS),
-		       node_page_state(NODE_DATA(dev->id), NUMA_FOREIGN),
-		       node_page_state(NODE_DATA(dev->id), NUMA_INTERLEAVE_HIT),
-		       node_page_state(NODE_DATA(dev->id), NUMA_LOCAL),
-		       node_page_state(NODE_DATA(dev->id), NUMA_OTHER));
+		       node_page_state_snapshot(NODE_DATA(dev->id), NUMA_HIT),
+		       node_page_state_snapshot(NODE_DATA(dev->id), NUMA_MISS),
+		       node_page_state_snapshot(NODE_DATA(dev->id),
+			       NUMA_FOREIGN),
+		       node_page_state_snapshot(NODE_DATA(dev->id),
+			       NUMA_INTERLEAVE_HIT),
+		       node_page_state_snapshot(NODE_DATA(dev->id), NUMA_LOCAL),
+		       node_page_state_snapshot(NODE_DATA(dev->id),
+			       NUMA_OTHER));
 }
 
 static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
@@ -194,7 +197,7 @@ static ssize_t node_read_vmstat(struct device *dev,
 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 		n += sprintf(buf+n, "%s %lu\n",
 			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
-			     node_page_state(pgdat, i));
+			     node_page_state_snapshot(pgdat, i));
 
 	return n;
 }
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 64e08ae..d65f28d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1466,7 +1466,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
 			seq_printf(m, "\n      %-12s %lu",
 				vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
-				node_page_state(pgdat, i));
+				node_page_state_snapshot(pgdat, i));
 		}
 	}
 	seq_printf(m,
-- 
2.7.4