linux-kernel - [PATCH 03/10] percpu: expose pcpu_nr_empty_pop_pages in pcpu

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Date:   Sat, 15 Jul 2017 22:23:08 -0400
From:   Dennis Zhou <dennisz@...com>
To:     Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>
CC:     <kernel-team@...com>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, Dennis Zhou <dennisszhou@...il.com>
Subject: [PATCH 03/10] percpu: expose pcpu_nr_empty_pop_pages in pcpu_stats

From: "Dennis Zhou (Facebook)" <dennisszhou@...il.com>

Percpu memory holds a minimum threshold of pages that are populated
in order to serve atomic percpu memory requests. This change makes it
easier to verify that there are a minimum number of populated pages
lying around.

Signed-off-by: Dennis Zhou <dennisszhou@...il.com>
---
 mm/percpu-internal.h | 1 +
 mm/percpu-stats.c    | 1 +
 mm/percpu.c          | 2 +-
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index cd2442e..c9158a4 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -36,6 +36,7 @@ extern spinlock_t pcpu_lock;
 
 extern struct list_head *pcpu_slot;
 extern int pcpu_nr_slots;
+extern int pcpu_nr_empty_pop_pages;
 
 extern struct pcpu_chunk *pcpu_first_chunk;
 extern struct pcpu_chunk *pcpu_reserved_chunk;
diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
index fa0f5de..44e561d 100644
--- a/mm/percpu-stats.c
+++ b/mm/percpu-stats.c
@@ -164,6 +164,7 @@ static int percpu_stats_show(struct seq_file *m, void *v)
 	PU(nr_max_chunks);
 	PU(min_alloc_size);
 	PU(max_alloc_size);
+	P("empty_pop_pages", pcpu_nr_empty_pop_pages);
 	seq_putc(m, '\n');
 
 #undef PU
diff --git a/mm/percpu.c b/mm/percpu.c
index bd4130a..9ec5fd4 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -160,7 +160,7 @@ static LIST_HEAD(pcpu_map_extend_chunks);
  * The number of empty populated pages, protected by pcpu_lock.  The
  * reserved chunk doesn't contribute to the count.
  */
-static int pcpu_nr_empty_pop_pages;
+int pcpu_nr_empty_pop_pages;
 
 /*
  * Balance work is used to populate or destroy chunks asynchronously.  We
-- 
2.9.3