Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 4270AC433C6
From:   Charan Teja Reddy <charante@codeaurora.org>
To:     akpm@linux-foundation.org, linux-mm@kvack.org
Cc:     linux-kernel@vger.kernel.org, vinmenon@codeaurora.org,
        Charan Teja Reddy <charante@codeaurora.org>
Subject: [PATCH] mm, memory_hotplug: update pcp lists everytime onlining a memory block
Date:   Sun,  2 Aug 2020 18:24:56 +0530
Message-Id: <1596372896-15336-1-git-send-email-charante@codeaurora.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When onlining a first memory block in a zone, pcp lists are not updated
thus pcp struct will have the default setting of ->high = 0,->batch = 1.
This means till the second memory block in a zone(if it have) is onlined
the pcp lists of this zone will not contain any pages because pcp's
->count is always greater than ->high thus free_pcppages_bulk() is
called to free batch size(=1) pages every time system wants to add a
page to the pcp list through free_unref_page(). To put this in a word,
system is not using benefits offered by the pcp lists when there is a
single onlineable memory block in a zone. Correct this by always
updating the pcp lists when memory block is onlined.

Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
---
 mm/memory_hotplug.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dcdf327..7f62d69 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -854,8 +854,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
 	node_states_set_node(nid, &arg);
 	if (need_zonelists_rebuild)
 		build_all_zonelists(NULL);
-	else
-		zone_pcp_update(zone);
+	zone_pcp_update(zone);
 
 	init_per_zone_wmark_min();
 
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation