Sergio R. Caprile wrote: > I have this raw api application which tcp_write()s 5 small (~20 bytes) > messages and then checks tcp_sndbuf() to send the biggest possible > chunk, but it ends up having to send a smaller chunk because an internal > queue gets full.
Actually, you have to understand TCP_SND_QUEUELEN to know what this limitation means: the snd_queuelen limitation is only a safety check that one pcb does not consume too many pbufs when you have multiple pcbs but only a limited number of pbufs. This limitation is somewhat overridden by the "new" TCP_OVERSIZE code which tries to only create one pbuf per tcp segment *when copying the data*. When not copying, data, the stack has no choice but to create one pbuf per tcp_write call. However, this is rather a different amount of memory consumed (PBUF_RAM or PBUF_POOL vs. PBUF_REF): e.g. you have enough RAM to create 30 PBUF_RAM, but the PBUF_REF pool holds x100 pbufs. So in applications where you mix these pbuf types, you might be better off to just set TCP_SND_QUEUELEN to a really high value that you never reach and implement the check to not enqueue too many pbufs on one connection yourself. Simon _______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users
