[Patch v2] cgroup: pretty format /proc/cgroups

[Patch v2] cgroup: pretty format /proc/cgroups

[Wei Yang]

Current /proc/cgroups looks like this:

 subsys_name    hierarchy       num_cgroups     enabled
cpuset  3       1       1
cpu     2       1       1
cpuacct 2       1       1
memory  4       71      1
freezer 5       1       1

Let's align the title and value. After this patch, it looks like this.

 subsys_name    hierarchy       num_cgroups     enabled
      cpuset            5                 1           1
         cpu            3                 1           1
     cpuacct            3                 1           1
      memory            2                71           1
     freezer            4                 1           1

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

---
v2: the title line is omitted for the start "#"

---
 kernel/cgroup/cgroup-v1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 81c9e0685948..5b177e0eca2c 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -664,7 +664,7 @@ int proc_cgroupstats_show(struct seq_file *m, void *v)
 	 */
 
 	for_each_subsys(ss, i)
-		seq_printf(m, "%s\t%d\t%d\t%d\n",
+		seq_printf(m, "%12s\t%9d\t%11d\t%7d\n",
 			   ss->legacy_name, ss->root->hierarchy_id,
 			   atomic_read(&ss->root->nr_cgrps),
 			   cgroup_ssid_enabled(i));
-- 
2.33.1

Re: [Patch v2] cgroup: pretty format /proc/cgroups

[Tejun Heo]

On Mon, Nov 15, 2021 at 01:12:53AM +0000, Wei Yang wrote:
> Current /proc/cgroups looks like this:
> 
>  subsys_name    hierarchy       num_cgroups     enabled
> cpuset  3       1       1
> cpu     2       1       1
> cpuacct 2       1       1
> memory  4       71      1
> freezer 5       1       1
> 
> Let's align the title and value. After this patch, it looks like this.
> 
>  subsys_name    hierarchy       num_cgroups     enabled
>       cpuset            5                 1           1
>          cpu            3                 1           1
>      cpuacct            3                 1           1
>       memory            2                71           1
>      freezer            4                 1           1
> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

So, I know it's silly but the file is dumb \t formatted (ie. single \t
between fields) and am slightly worried that changing the format might break
some dumb userspace tooling. Given that the information isn't really needed
for cgroup2 anyway, it prolly is better to leave it as-is, I think.

Thanks.

-- 
tejun

Re: [Patch v2] cgroup: pretty format /proc/cgroups

[Michal Koutný]

Hello.

On Mon, Nov 15, 2021 at 01:12:53AM +0000, Wei Yang <richard.weiyang@gmail.com> wrote:
> Let's align the title and value. After this patch, it looks like this.

For machines this change may come as a surprise (so better not change
it).

For humans (for instance column from util-linux)

$ column -t /proc/cgroups
#subsys_name  hierarchy  num_cgroups  enabled
cpuset        11         2            1
cpu           4          9            1
cpuacct       4          9            1
...

Michal

Re: [Patch v2] cgroup: pretty format /proc/cgroups

[Wei Yang]

On Tue, Nov 16, 2021 at 07:00:17PM +0100, Michal Koutn? wrote:
>Hello.
>
>On Mon, Nov 15, 2021 at 01:12:53AM +0000, Wei Yang <richard.weiyang@gmail.com> wrote:
>> Let's align the title and value. After this patch, it looks like this.
>
>For machines this change may come as a surprise (so better not change
>it).
>
>For humans (for instance column from util-linux)
>
>$ column -t /proc/cgroups
>#subsys_name  hierarchy  num_cgroups  enabled
>cpuset        11         2            1
>cpu           4          9            1
>cpuacct       4          9            1
>...
>

This is helpful, thanks.

>Michal

-- 
Wei Yang
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