From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Tomlin Subject: [PATCH] memcg: add support to generate the total count of children from root Date: Tue, 24 Nov 2020 10:58:36 +0000 Message-ID: <20201124105836.713371-1-atomlin@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606215521; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=93iiWXlJJ6IXGgnGTBAqbCv2bSJUjXfqZiq9BMzLTt8=; b=U/is7sloglMBZMt3jdw1KgxWeNHZU3N8l+xPagEIp6xVArivT3+R7PlwZXDOSXAnNCkmGB NBSPkdZaPqLGS3R4eSru7DP69uQKNdKsqp0DN6XFmk5FIXYkQ5hZuzRh7H+1oBzlhJFffq XeWivHlDTIJCJCq0gzmVtQY3c1sjw1k= List-ID: Content-Type: text/plain; charset="us-ascii" To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org 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 --- 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 @@ -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