Re: [tipc-discussion] Sends Hanging

[Duzan, G. D <Gar...@fi...>]

   As for the stuck process, here is a /proc/{pid}/stack (from 5.14.0-570.25.1.el9_6.x86_64):

[<0>] wait_woken+0x50/0x60
[<0>] __tipc_sendmsg+0x28b/0x6d0 [tipc]
[<0>] tipc_sendmsg+0x31/0x50 [tipc]
[<0>] ____sys_sendmsg+0x388/0x3b0
[<0>] ___sys_sendmsg+0x88/0xd0
[<0>] __sys_sendmsg+0x59/0xa0
[<0>] do_syscall_64+0x5c/0xe0
[<0>] entry_SYSCALL_64_after_hwframe+0x78/0x80

Gary Duzan
IT Architect Senior
GT.M Core Team
________________________________
From: Duzan, Gary D <Gar...@fi...>
Sent: Wednesday, July 16, 2025 8:22 AM
To: Tung Nguyen <tun...@en...>; Duzan, Gary D via tipc-discussion <tip...@li...>
Subject: Re: Sends Hanging

Tung Nguyen
7/16/2025 5:20 AM
What command did you use to adjust the window size ?
# tipc link set window 51 link 1423f2c2ed9:enp129s0f0np0-04320114767:eno12399np0
# tipc link set window 100 link 1423f2c2ed9:enp129s0f0np0-04320114767:eno12399np0
# tipc link set window 500 link 1423f2c2ed9:enp129s0f0np0-04320114767:eno12399np0
# tipc link statistics show
[...]
Link <1423f2c2ed9:enp129s0f0np0-04320114767:eno12399np0>
  ACTIVE  MTU:1500  Priority:10  Tolerance:1500 ms  Window:50 packets
  RX packets:2004240 fragments:634446/44511 bundles:4826/22566
  TX packets:3063887 fragments:2068092/689014 bundles:2035/10681
  TX profile sample:267 packets average:1375 octets
  0-64:69% -256:1% -1024:0% -4096:0% -16384:30% -32768:0% -66000:0%
  RX states:2855437 probes:1363107 naks:8613 defs:92196 dups:19121
  TX states:2771466 probes:1363580 naks:2608352 acks:36820 retrans:2382
  Congestion link:938  Send queue max:0 avg:0

# tipc link get window link 1423f2c2ed9:enp129s0f0np0-04320114767:eno12399np0
50

That was on an Ubuntu 24.04.2 server, but I get the same on RHEL 9.6 and Fedora 42.

   Thanks.
Gary Duzan
IT Architect Senior
GT.M Core Team

________________________________
From: Tung Nguyen <tun...@en...>
Sent: Wednesday, July 16, 2025 5:20 AM
To: Duzan, Gary D <Gar...@fi...>; Duzan, Gary D via tipc-discussion <tip...@li...>
Subject: RE: Sends Hanging


>   I'm trying to diagnose an issue with TIPC datagram anycast or group broadcast sends hanging when the receiver processes on another host are waiting in either poll or recvmsg. These are relatively fast machines with 10g ethernet connecting them, and varying amounts of background activity.
It seems a forever link congestion.
> My first thought was to try adjusting the window settings, but the media/bearer window is maxed out, and the link windows seem to be fixed at 50. Is this the expected behavior?
What command did you use to adjust the window size ?



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