From: Andreas Fink <afink@list.fink.org>
To: linux-sctp@vger.kernel.org
Subject: Re: sctp discarding received data chunks
Date: Fri, 09 Oct 2020 07:24:41 +0000 [thread overview]
Message-ID: <CC1FDC9B-F273-475A-98C5-000ADC395BB0@list.fink.org> (raw)
In-Reply-To: <e377e7e2a87e4f078e7a6d82992cfda0@AcuMS.aculab.com>
Can you see this issue with the 5.4 kernel too?
I did yesterday some testing by upgrading kernel from 5.4 to 5.7 and I run into all sorts of links going off after a while so I had to revert back.
5.4 is stable for me. 5.7 is not. And I have lots of M2PA and M3UA connections like you
> On 8 Oct 2020, at 23:46, David Laight <David.Laight@ACULAB.COM> wrote:
>
> One of my local tests (that I run quite often) failed in a 'new and exciting way'.
> I sent 510 messages through an M3UA-MTP2-M3UA link and only got ~350 at the far end.
> (This is part of my SS7+TCAP regression test - gets run a lot.)
> Usually I can find 'lost' messages logged as discarded due to my own flow control.
> In this case there is no sign of any error traces.
> I expect to have each message traced 6 times (on each send and receive)
> but the missing messages are only traced 5 times.
>
> Now /proc/net/sctp/snmp has SctpInDataChunksDiscards set to 163,
> this matches the number of messages I'm missing.
> Any idea how I can find out why one (or more) the SCTP connections (which are still
> connected - unless there is a power cut) has discarded a lot of receive packets?
>
> Each M3UA link is actually 4 SCTP connections (TCP style 1-1).
> All are loopback connected to 127.0.0.1 or ::1 (the assocs print is 'interesting').
> The local port is 'random' the listening port 2905 or 2906.
> I'd expect the data to loadshare evenly between them but I've not checked the actual
> distribution.
> The packet data contains a sequence number, I'm missing all the x1, x2, x9, xa
> and half the x6 and xe packets - so I think at least one of the sctp connections
> is just discarding the receive chunks.
> (I'll sort out which one tomorrow.)
>
> This is a 5.6.0-rc7 kernel.
> I've not seen anything like this before - I've run this same test for
> over 10 years, probably going back to at least 2.6.28.
>
> Data chunks will have gone though all the connections when they were
> initialised.
>
> Is there anything anywhere that indicates why a data chunk was dropped?
>
> David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Fink <afink@list.fink.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>
Subject: Re: sctp discarding received data chunks
Date: Fri, 9 Oct 2020 09:24:41 +0200 [thread overview]
Message-ID: <CC1FDC9B-F273-475A-98C5-000ADC395BB0@list.fink.org> (raw)
Message-ID: <20201009072441.TTTpPVsAmSpxfby_7RdvD7RKQO9EmiYQp1DeNl4Ezvc@z> (raw)
In-Reply-To: <e377e7e2a87e4f078e7a6d82992cfda0@AcuMS.aculab.com>
Can you see this issue with the 5.4 kernel too?
I did yesterday some testing by upgrading kernel from 5.4 to 5.7 and I run into all sorts of links going off after a while so I had to revert back.
5.4 is stable for me. 5.7 is not. And I have lots of M2PA and M3UA connections like you
> On 8 Oct 2020, at 23:46, David Laight <David.Laight@ACULAB.COM> wrote:
>
> One of my local tests (that I run quite often) failed in a 'new and exciting way'.
> I sent 510 messages through an M3UA-MTP2-M3UA link and only got ~350 at the far end.
> (This is part of my SS7+TCAP regression test - gets run a lot.)
> Usually I can find 'lost' messages logged as discarded due to my own flow control.
> In this case there is no sign of any error traces.
> I expect to have each message traced 6 times (on each send and receive)
> but the missing messages are only traced 5 times.
>
> Now /proc/net/sctp/snmp has SctpInDataChunksDiscards set to 163,
> this matches the number of messages I'm missing.
> Any idea how I can find out why one (or more) the SCTP connections (which are still
> connected - unless there is a power cut) has discarded a lot of receive packets?
>
> Each M3UA link is actually 4 SCTP connections (TCP style 1-1).
> All are loopback connected to 127.0.0.1 or ::1 (the assocs print is 'interesting').
> The local port is 'random' the listening port 2905 or 2906.
> I'd expect the data to loadshare evenly between them but I've not checked the actual
> distribution.
> The packet data contains a sequence number, I'm missing all the x1, x2, x9, xa
> and half the x6 and xe packets - so I think at least one of the sctp connections
> is just discarding the receive chunks.
> (I'll sort out which one tomorrow.)
>
> This is a 5.6.0-rc7 kernel.
> I've not seen anything like this before - I've run this same test for
> over 10 years, probably going back to at least 2.6.28.
>
> Data chunks will have gone though all the connections when they were
> initialised.
>
> Is there anything anywhere that indicates why a data chunk was dropped?
>
> David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
next prev parent reply other threads:[~2020-10-09 7:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 21:46 sctp discarding received data chunks David Laight
2020-10-08 21:46 ` David Laight
2020-10-09 7:24 ` Andreas Fink [this message]
2020-10-09 7:24 ` Andreas Fink
2020-10-09 7:57 ` David Laight
2020-10-09 7:57 ` David Laight
2020-10-09 11:13 ` David Laight
2020-10-09 11:13 ` David Laight
2020-10-09 13:03 ` David Laight
2020-10-09 13:03 ` David Laight
2020-10-10 2:35 ` Xin Long
2020-10-10 2:35 ` Xin Long
2020-10-10 15:10 ` David Laight
2020-10-10 15:10 ` David Laight
2020-10-11 8:33 ` Andreas Fink
2020-10-11 8:33 ` Andreas Fink
2020-10-11 15:28 ` David Laight
2020-10-11 15:28 ` David Laight
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