#268 Client reports wrong speed since 7065f57

[Tom Barbette]

Since 7065f57 the client reports random garbage speed, see below.

Maybe this is due to the use of a high speed link? Everything else on this machine is quite the default, Ubuntu 20.04 LTS.

With 7065f57:

src/iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size:  128 KByte (default)
------------------------------------------------------------
[  1] local 10.100.1.1 port 5001 connected with 10.100.1.2 port 40698 (icwnd/mss/irtt=14/1448/59)
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-2.00 sec  5.44 GBytes  23.3 Gbits/sec

iperf -c 10.100.1.1 -t 2[13:22:31]
------------------------------------------------------------
Client connecting to 10.100.1.1, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  1] local 10.100.1.2 port 40698 connected with 10.100.1.1 port 5001 (icwnd/mss/irtt=14/1448/187)
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-2.01 sec  60.0 Bytes   238 bits/sec

The expected behavior with 7065f57~2 (~1 is creating problems):

src/iperf -c 10.100.1.1 -t 2
------------------------------------------------------------
Client connecting to 10.100.1.1, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  1] local 10.100.1.2 port 40704 connected with 10.100.1.1 port 5001 (icwnd/mss/irtt=14/1448/262)
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-2.01 sec  5.59 GBytes  23.9 Gbits/sec
grincheux (1) [1578] % /etinfo/users2/tbarbette/workspace/npf/build/iperf2-git/src/iperf -c 10.100.1.1 -t 2

[Tom Barbette]

Note that the server is reporting the correct speed.

[Robert McMahon]

I haven't reproduced this. Can you provide the output of iperf -v?

[Tom Barbette]

~2 :
iperf version 2.1.n (18 April 2023) pthreads
7065f57:
iperf version 2.1.n (20 April 2023) pthreads

[Robert McMahon]

Fixed here. Use -e for a work around on previous versions.

[root@localhost iperf2-code]# src/iperf -c 192.168.1.26 -t 2
------------------------------------------------------------
Client connecting to 192.168.1.26, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.28 port 45098 connected with 192.168.1.26 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-2.04 sec   218 MBytes   895 Mbits/sec
[root@localhost iperf2-code]# src/iperf -c 192.168.1.26 -t 2 -e
------------------------------------------------------------
Client connecting to 192.168.1.26, TCP port 5001 with pid 42286 (1/0 flows/load)
Write buffer size: 131072 Byte
TCP congestion control using cubic
TOS set to 0x0 (Nagle on)
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.28%eno1 port 41040 connected with 192.168.1.26 port 5001 (sock=3) (icwnd/mss/irtt=14/1448/290) (ct=0.33 ms) on 2023-08-10 14:41:04.317 (PDT)
[ ID] Interval        Transfer    Bandwidth       Write/Err  Rtry     Cwnd/RTT(var)        NetPwr
[  1] 0.00-2.04 sec   222 MBytes   913 Mbits/sec  1776/0         0      605K/2548(117) us  44780