From: Aaron Tomlin <atomlin@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH] memcg: add support to generate the total count of children from root
Date: Tue, 24 Nov 2020 10:58:36 +0000 [thread overview]
Message-ID: <20201124105836.713371-1-atomlin@redhat.com> (raw)
Each memory-controlled cgroup is assigned a unique ID and the total
number of memory cgroups is limited to MEM_CGROUP_ID_MAX.
This patch provides the ability to determine the number of
memory cgroups from the root memory cgroup, only.
A value of 1 (i.e. self count) is returned if there are no children.
For example, the number of memory cgroups can be established by
reading the /sys/fs/cgroup/memory/memory.total_cnt file.
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
---
mm/memcontrol.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 29459a6ce1c7..a4f7cb40e233 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4535,6 +4535,19 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
return 0;
}
+static int mem_cgroup_total_count_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct mem_cgroup *iter, *memcg = mem_cgroup_from_css(css);
+ int num = 0;
+
+ for_each_mem_cgroup_tree(iter, memcg)
+ num++;
+
+ /* Returns 1 (i.e. self count) if no children. */
+ return num;
+}
+
#ifdef CONFIG_CGROUP_WRITEBACK
#include <trace/events/writeback.h>
@@ -5050,6 +5063,11 @@ static struct cftype mem_cgroup_legacy_files[] = {
.write_u64 = mem_cgroup_oom_control_write,
.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
},
+ {
+ .name = "total_cnt",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .read_u64 = mem_cgroup_total_count_read,
+ },
{
.name = "pressure_level",
},
--
2.26.2
next reply other threads:[~2020-11-24 10:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 10:58 Aaron Tomlin [this message]
2020-11-24 11:26 ` [PATCH] memcg: add support to generate the total count of children from root Michal Hocko
2020-11-24 13:36 ` Aaron Tomlin
[not found] ` <CANfR36hyrqXjk2tL03GzCk6rn6sCD7Sd811soBsZC3dHY0h9fQ@mail.gmail.com>
2020-11-24 13:36 ` Michal Hocko
2020-11-24 13:47 ` Aaron Tomlin
2020-11-26 11:02 ` Aaron Tomlin
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