On: Raspberry Pi Pico does line rate 100M Ethernet

[montecarl]

Why is the transfer rate non-linear with respect to the system clock? At 100 MHz the rate is 1.38 Mbit/s and at 200 Mhz it is 65.4 Mbit/s.

[nyrikki → montecarl]

Latency kills...and Ethernet uses exponential backoff.

[crote → nyrikki]

More specifically TCP uses exponential backoff. Ethernet will happily keep drowning you in packages at line rate, if I'm not mistaken.

[daymanstep → crote]

CSMA/CD does use exponential back off, though I'm not sure if anyone is still using it.

[fach → daymanstep]

This is only for half-duplex ethernet communication so no one apart from some archaic systems.

[ryan-c → fach]

Like WiFi?

[edward28 → ryan-c]

CSMA/CA but close.

[pantalaimon → fach]

There is also 10Base-T1 which is a rather recent addition.

[KennyBlanken → crote]

> Ethernet will happily keep drowning you in packages at line rate, if I'm not mistaken.

It's a physical layer, so yeah, of course it will.

[vardump → montecarl]

Maybe a lot of CRC errors or something. Just a guess.

[rscott2049 → montecarl]

Wish I could answer that! All I can guess is that the slower processing speed creates a bottleneck in the LWIP stack somewhere...