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

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Date:	Mon, 3 Oct 2011 16:26:41 +0400
From:	Glauber Costa <glommer@...allels.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
CC:	<linux-kernel@...r.kernel.org>, <paul@...lmenage.org>,
	<lizf@...fujitsu.com>, <kamezawa.hiroyu@...fujitsu.com>,
	<ebiederm@...ssion.com>, <davem@...emloft.net>,
	<gthelen@...gle.com>, <netdev@...r.kernel.org>,
	<linux-mm@...ck.org>, <avagin@...allels.com>
Subject: Re: [PATCH v4 7/8] Display current tcp memory allocation in kmem
 cgroup

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@...allels.com>
>>>> CC: David S. Miller<davem@...emloft.net>
>>>> CC: Hiroyouki Kamezawa<kamezawa.hiroyu@...fujitsu.com>
>>>> CC: Eric W. Biederman<ebiederm@...ssion.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.

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