Message-ID: <20201014053429.GI4251@kernel.org>
Date:   Wed, 14 Oct 2020 08:34:29 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Muchun Song <songmuchun@...edance.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
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        Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [External] Re: [PATCH] mm: proc: add Sock to /proc/meminfo

On Tue, Oct 13, 2020 at 08:21:13AM -0700, Randy Dunlap wrote:
> 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@...il.com> wrote:
> >>>>>
> >>>>> On 10/12/20 10:39 AM, Muchun Song wrote:
> >>>>>> On Mon, Oct 12, 2020 at 3:42 PM Eric Dumazet <edumazet@...gle.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@...ux.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@...ux.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?

Ah, these are in 4k pages, AFAIU.
And, as it seems /proc/net/sockstat lacks a description in proc.5 at
all...

> thanks.
> -- 
> ~Randy
> 
> 

-- 
Sincerely yours,
Mike.

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