Re: [lwip-users] TCP tuning

[leon . woestenberg]

Hello,

This is what I have been using. Getting a very constant 27 kibibytes/second
using a 18MHz 16-bit microcontroller.

#define TCP_MSS                 522

/* TCP sender buffer space (bytes). */
#define TCP_SND_BUF             1024

/* TCP sender buffer space (pbufs). This must be at least = 2 *
   TCP_SND_BUF/TCP_MSS for things to work. */
#define TCP_SND_QUEUELEN        (4 * TCP_SND_BUF/TCP_MSS)

/* TCP receive window. */
#define TCP_WND                 1024


Besides this, we noted a 30% performance increase (20 to 27 KB/s) when
using zero-copy pbufs (PBUF_ROM) instead of first copying to  PBUF_RAM.

Note however that PBUF_ROM does not allow packet queueing if your
data is non-const.

Regards, Leon.