Re: [lwip-users] FreeRTOS + Lwip, transmit gets BLOCKED

[Simon Wilton]

Hi Marek

There is an automatic back-off mechanism designed to stop nodes flooding the network with small TCP messages called Nagle algorithm. Check if you are being blocked by that. You can turn it off - i think on a per connection basis.

There is also a similar thread that I found when i was looking at a similar problem http://lwip.100.n7.nabble.com/lwIP-hangs-on-transfers-with-many-short-packets-td11044.html

BR

Simon

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From: lwip-users <lwip-users-bounces+simon.wilton=address@hidden> on behalf of mjanicek <address@hidden>
Sent: 03 March 2020 08:46
To: address@hidden <address@hidden>
Subject: [lwip-users] FreeRTOS + Lwip, transmit gets BLOCKED

 

Hello,
 
I have STM32F407 running FreeRTOS + Lwip (netconn). I have several tasks.
Only one Task1 is transmitting continously small packets (85 bytes) every 5
miliseconds on ethernet.
Transmitting is randomly paused for a long time (cca 1-2 sec) then it is
resumed.
 
Task1 in function lwip_netconn_do_write() takes the semaphore by
sys_arch_sem_wait(LWIP_API_MSG_SEM(msg), 0) and Task1 gets BLOCKED. It
remains blocked for cca 1-2 seconds.
When tcpip_thread in function lwip_netconn_do_writemore() gives semaphore by
sys_sem_signal(op_completed_sem) then Task1 gets finally READY.
 
Please do you have idea why this is happening for such a long time?
 
Thanks
Marek




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