buglwIP - A Lightweight TCP/IP stack - Bugs: bug #64638, "iperf -r" does not work...


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bug #64638: "iperf -r" does not work for all "-M"

Submitter:  Hardy Griech <rgrr>
Submitted:  Fri 08 Sep 2023 06:25:38 PM UTC
Category:  None Severity:  3 - Normal
Item Group:  None Status:  None
Privacy:  Public Assigned to:  None
Open/Closed:  Open Planned Release:  None
lwIP version:  git head

Wed 27 Sep 2023 07:04:53 PM UTC, comment #1: 

Could you provide a littel more input? I don't know if "txlen != 0" is correct. This should probably be somehow connected to the "-M" size or we risk having low throughput when we're low on memory. The current "txlen" check is there for a reason, after all!

Simon Goldschmidt <goldsimon>
Group administrator
Fri 08 Sep 2023 06:25:38 PM UTC, original submission:  

This is true at least for the combination lwIP/TinyUSB.

On my Linux host, "iperf -r" did not work for small values of "-M <mss>".  Reason was that the loop in lwiperf_tcp_client_send_more() is to restrictive.  It aborts when "txlen >= (TCP_MSS / 2)".

For my setup it is needed, that this has to be changed to "txlen != 0", because otherwise there is under described circumstances no transmission and thus no lwiperf_tcp_client_sent() which retriggers send_more.

Should I provide the patch?

Hardy Griech <rgrr>


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