Re: [avrdude-dev] Serial port latency under linux

[Jan-Hinnerk Reichert]

Am Freitag, 9. Mai 2003 20:40 schrieb Jan-Hinnerk Reichert:
> Hi,
>
> just some small info you might include in the docs somewhere:
>
> Under Linux (don't know about other OS) you can switch a serial port to low
> latency by entering the following in a console
>
> > setserial /dev/ttySx low_latency
>
> This gives a great speed improvement with avr910-programmers.
>
>  Jan-Hinnerk

Just another interesting observation about speed:

With low_latency, I still needed about 17s for reading a 8515, but the 
theoretical minimum (in my setup) is 7s.

After some time of suspecting scheduling latency, I tried a rather stupid 
thing and set my uart to 16450 (before it was a 16550A ;-)

# setserial /dev/ttySx uart 16450 low_latency

Now avrdude is reading a 8515 in 8s ;-)
Seems like there is some strange FIFO magic involved in the additional delay.

BTW: The original avr910 should be much slower, IIRC.

 Jan-Hinnerk