linux-kernel - [PATCH 1/5] mm/memory_hotplug: Spare unnecessary calls to node_set

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Date:   Wed, 19 Sep 2018 12:08:15 +0200
From:   Oscar Salvador <osalvador@...hadventures.net>
To:     akpm@...ux-foundation.org
Cc:     mhocko@...e.com, dan.j.williams@...el.com, david@...hat.com,
        Pavel.Tatashin@...rosoft.com, Jonathan.Cameron@...wei.com,
        yasu.isimatu@...il.com, malat@...ian.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Oscar Salvador <osalvador@...e.de>
Subject: [PATCH 1/5] mm/memory_hotplug: Spare unnecessary calls to node_set_state

From: Oscar Salvador <osalvador@...e.de>

In node_states_check_changes_online, we check if the node will
have to be set for any of the N_*_MEMORY states after the pages
have been onlined.

Later on, we perform the activation in node_states_set_node.
Currently, in node_states_set_node we set the node to N_MEMORY
unconditionally.
This means that we call node_set_state for N_MEMORY every time
pages go online, but we only need to do it if the node has not yet been
set for N_MEMORY.

Fix this by checking status_change_nid.

Signed-off-by: Oscar Salvador <osalvador@...e.de>
---
 mm/memory_hotplug.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 38d94b703e9d..63facfc57224 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -753,7 +753,8 @@ static void node_states_set_node(int node, struct memory_notify *arg)
 	if (arg->status_change_nid_high >= 0)
 		node_set_state(node, N_HIGH_MEMORY);
 
-	node_set_state(node, N_MEMORY);
+	if (arg->status_change_nid >= 0)
+		node_set_state(node, N_MEMORY);
 }
 
 static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
-- 
2.13.6