Regards
Alister
| Alister
Fisher Senior Software Developer  16/52 Corporate Blvd, Bayswater, VIC, 3153, AUSTRALIA T: +61 3 8400 4566 alister@advateklights.com www.advateklights.com |
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-----Original Message-----
From: lwip-users <lwip-users-bounces+alister=advateklights.com@nongnu.org> On Behalf Of goldsimon@gmx.de
Sent: Thursday, 25 March 2021 6:11 AM
To: Mailing list for lwIP users <lwip-users@nongnu.org>
Subject: Re: [lwip-users] Why does enabling Debug fix this tcp_sndbuf()
Am 24.03.2021 um 16:32 schrieb Osborne, David:
> Hi All,
>
>
>
> I’m using LwIP + FreeRTOS + Sockets on STM32H7 with external SDRAM and
> FLASH (Ethernet buffers are internal). It works well until the server
> has to send a very large message (> 18Kbytes). One in five attempts
> ends in failure. During the transmission tcp_sndbuf() (in api_msg.c)
> returns zero and the connection falls over. From what I’ve read, a
> common cause is that it’s waiting for an outstanding ACK. I’m no
> expert, but it looks like the ACK has been sent (see Wireshark attachment).
>
>
>
> When I enable certain debug settings it works every time (don’t you
> hate that).
That's an indication that there's something wrong that's hidden by either longer runtime (more debug code enabled) or by heavier cache usage (more code/data in the caches).
In any case, I'd suggest thoroughly review the OS port and the netif driver regarding caching issues and/or threading issues (where interrupt vs. thread/main loop also counts in).
Regards,
Simon
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