linux-kernel - [PATCH RFC] mm, proc: add PcpFree to meminfo

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Date:   Tue, 16 Aug 2022 16:44:26 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-mm@...ck.org>
CC:     <linux-kernel@...r.kernel.org>, Liu Shixin <liushixin2@...wei.com>,
        "Kefeng Wang" <wangkefeng.wang@...wei.com>
Subject: [PATCH RFC] mm, proc: add PcpFree to meminfo

From: Liu Shixin <liushixin2@...wei.com>

The page on pcplist could be used, but not counted into memory free or
avaliable, and pcp_free is only showed by show_mem(). Since commit
d8a759b57035 ("mm, page_alloc: double zone's batchsize"), there is a
significant decrease in the display of free memory, with a large number
of cpus and nodes, the number of pages in the percpu list can be very
large, so it is better to let user to know the pcp count.

Signed-off-by: Liu Shixin <liushixin2@...wei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 drivers/base/node.c | 14 +++++++++++++-
 fs/proc/meminfo.c   |  9 +++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index eb0f43784c2b..846864e45db6 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -375,6 +375,9 @@ static ssize_t node_read_meminfo(struct device *dev,
 	struct sysinfo i;
 	unsigned long sreclaimable, sunreclaimable;
 	unsigned long swapcached = 0;
+	unsigned long free_pcp = 0;
+	struct zone *zone;
+	int cpu;
 
 	si_meminfo_node(&i, nid);
 	sreclaimable = node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B);
@@ -382,9 +385,17 @@ static ssize_t node_read_meminfo(struct device *dev,
 #ifdef CONFIG_SWAP
 	swapcached = node_page_state_pages(pgdat, NR_SWAPCACHE);
 #endif
+	for_each_populated_zone(zone) {
+		if (zone_to_nid(zone) != nid)
+			continue;
+		for_each_online_cpu(cpu)
+			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
+	}
+
 	len = sysfs_emit_at(buf, len,
 			    "Node %d MemTotal:       %8lu kB\n"
 			    "Node %d MemFree:        %8lu kB\n"
+			    "Node %d PcpFree:        %8lu kB\n"
 			    "Node %d MemUsed:        %8lu kB\n"
 			    "Node %d SwapCached:     %8lu kB\n"
 			    "Node %d Active:         %8lu kB\n"
@@ -397,7 +408,8 @@ static ssize_t node_read_meminfo(struct device *dev,
 			    "Node %d Mlocked:        %8lu kB\n",
 			    nid, K(i.totalram),
 			    nid, K(i.freeram),
-			    nid, K(i.totalram - i.freeram),
+			    nid, K(free_pcp),
+			    nid, K(i.totalram - i.freeram - free_pcp),
 			    nid, K(swapcached),
 			    nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
 				   node_page_state(pgdat, NR_ACTIVE_FILE)),
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 6e89f0e2fd20..672c784dfc8a 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -38,6 +38,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	unsigned long pages[NR_LRU_LISTS];
 	unsigned long sreclaimable, sunreclaim;
 	int lru;
+	unsigned long free_pcp = 0;
+	struct zone *zone;
+	int cpu;
 
 	si_meminfo(&i);
 	si_swapinfo(&i);
@@ -55,8 +58,14 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	sreclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B);
 	sunreclaim = global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B);
 
+	for_each_populated_zone(zone) {
+		for_each_online_cpu(cpu)
+			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
+	}
+
 	show_val_kb(m, "MemTotal:       ", i.totalram);
 	show_val_kb(m, "MemFree:        ", i.freeram);
+	show_val_kb(m, "PcpFree:        ", free_pcp);
 	show_val_kb(m, "MemAvailable:   ", available);
 	show_val_kb(m, "Buffers:        ", i.bufferram);
 	show_val_kb(m, "Cached:         ", cached);
-- 
2.35.3