Re: [PATCH v4 7/8] Display current tcp memory allocation in kmem cgroup

Glauber Costa
2011-10-03T12:27:31Z

On 10/03/2011 04:25 PM, Kirill A. Shutemov wrote:
> On Mon, Oct 03, 2011 at 04:19:18PM +0400, Glauber Costa wrote:
>> On 10/03/2011 04:14 PM, Kirill A. Shutemov wrote:
>>> On Mon, Oct 03, 2011 at 02:18:42PM +0400, Glauber Costa wrote:
>>>> This patch introduces kmem.tcp_current_memory file, living in the
>>>> kmem_cgroup filesystem. It is a simple read-only file that displays the
>>>> amount of kernel memory currently consumed by the cgroup.
>>>>
>>>> Signed-off-by: Glauber Costa<glommer@parallels.com>
>>>> CC: David S. Miller<davem@davemloft.net>
>>>> CC: Hiroyouki Kamezawa<kamezawa.hiroyu@jp.fujitsu.com>
>>>> CC: Eric W. Biederman<ebiederm@xmission.com>
>>>> ---
>>>> Documentation/cgroups/memory.txt | 1 +
>>>> mm/memcontrol.c | 11 +++++++++++
>>>> 2 files changed, 12 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
>>>> index 1ffde3e..f5a539d 100644
>>>> --- a/Documentation/cgroups/memory.txt
>>>> +++ b/Documentation/cgroups/memory.txt
>>>> @@ -79,6 +79,7 @@ Brief summary of control files.
>>>> memory.independent_kmem_limit # select whether or not kernel memory limits are
>>>> independent of user limits
>>>> memory.kmem.tcp.max_memory # set/show hard limit for tcp buf memory
>>>> + memory.kmem.tcp.current_memory # show current tcp buf memory allocation
>>>
>>> Both are in pages, right?
>>> Shouldn't it be scaled to bytes and named uniform with other memcg file?
>>> memory.kmem.tcp.limit_in_bytes/usage_in_bytes.
>>>
>> You are absolutely correct.
>> Since the internal tcp comparison works, I just ended up never noticing
>> this.
>
> Should we have failcnt and max_usage_in_bytes for tcp as well?
>

Well, we get a fail count from the tracer anyway, so I don't really see
a need for that. I see value in having it for the slab allocation
itself, but since this only controls the memory pressure framework, I
think we can live without it.

That said, this is not a strong opinion. I can add it if you'd prefer.