Re: [External] Re: [PATCH] mm: proc: add Sock to /proc/meminfo

Randy Dunlap
2020-10-13T15:21:39Z

On 10/13/20 8:12 AM, Mike Rapoport wrote:
> On Tue, Oct 13, 2020 at 07:43:59AM -0700, Randy Dunlap wrote:
>> On 10/13/20 1:09 AM, Mike Rapoport wrote:
>>> On Mon, Oct 12, 2020 at 05:53:01PM +0800, Muchun Song wrote:
>>>> On Mon, Oct 12, 2020 at 5:24 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>>>>>
>>>>> On 10/12/20 10:39 AM, Muchun Song wrote:
>>>>>> On Mon, Oct 12, 2020 at 3:42 PM Eric Dumazet <edumazet@google.com> wrote:
>>>>
>>>> We are not complaining about TCP using too much memory, but how do
>>>> we know that TCP uses a lot of memory. When I firstly face this problem,
>>>> I do not know who uses the 25GB memory and it is not shown in the /proc/meminfo.
>>>> If we can know the amount memory of the socket buffer via /proc/meminfo, we
>>>> may not need to spend a lot of time troubleshooting this problem. Not everyone
>>>> knows that a lot of memory may be used here. But I believe many people
>>>> should know /proc/meminfo to confirm memory users.
>>>
>>> If I undestand correctly, the problem you are trying to solve is to
>>> simplify troubleshooting of memory usage for people who may not be aware
>>> that networking stack can be a large memory consumer.
>>>
>>> For that a paragraph in 'man 5 proc' maybe a good start:
>>>
>>> >From ddbcf38576d1a2b0e36fe25a27350d566759b664 Mon Sep 17 00:00:00 2001
>>> From: Mike Rapoport <rppt@linux.ibm.com>
>>> Date: Tue, 13 Oct 2020 11:07:35 +0300
>>> Subject: [PATCH] proc.5: meminfo: add not anout network stack memory
>>> consumption
>>>
>>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>>> ---
>>> man5/proc.5 | 8 ++++++++
>>> 1 file changed, 8 insertions(+)
>>>
>>> diff --git a/man5/proc.5 b/man5/proc.5
>>> index ed309380b..8414676f1 100644
>>> --- a/man5/proc.5
>>> +++ b/man5/proc.5
>>> @@ -3478,6 +3478,14 @@ Except as noted below,
>>> all of the fields have been present since at least Linux 2.6.0.
>>> Some fields are displayed only if the kernel was configured
>>> with various options; those dependencies are noted in the list.
>>> +.IP
>>> +Note that significant part of memory allocated by the network stack
>>> +is not accounted in the file.
>>> +The memory consumption of the network stack can be queried
>>> +using
>>> +.IR /proc/net/sockstat
>>> +or
>>> +.BR ss (8)
>>> .RS
>>> .TP
>>> .IR MemTotal " %lu"
>>
>> Hi Mike,
>>
>> Could you tell us what units those values are in?
>> or is that already explained somewhere else?
>
> It is described a few lines above and anyway, "MemTotal" is a part of
> the diff context ;-)

with no units AFAICT.

But I was unclear. I wasn't referring to /proc/meminfo, but instead
to /proc/net/sockstat and its units:

sockets: used 1224
TCP: inuse 11 orphan 1 tw 1 alloc 26 mem 3
UDP: inuse 4 mem 2
UDPLITE: inuse 0
RAW: inuse 0
FRAG: inuse 0 memory 0

E.g., for TCP and UDP, are those socket counts or some unit of memory?
If units of memory, what unit size?

thanks.
--
~Randy