ace fifo and interrupt trouble with serial dev

From: Armin Ollig <armin_at_metzelkueche.tabu.uni-bonn.de>
Date: Tue, 08 Aug 2000 15:24:55 +0200 (CEST)

hi managers,

Hardware: AlphaPC 164
OS: Tru64 5.0a

I have an ISDN TA attached to tty01, i connect to my ISP with 64kbit
using pppd (speed to the serial dev is 115200).
When downloading at high speeds (7k) vmstat reports 8k interrupts per
second, which would mean that the kernel gets every byte from the
serial port via an interrupt, not using the 16byte fifo.

This means that a 7.2kb download use 50% of my 500mhz CPU and if the load
is high download speed goes down :(

I read ace(7) and looked at the header file, but still dont know how to
turn on the fifo for that port (i also checked the boards docs and it
actually *has* a fifo installed).

Any advice ?
Thanks in advance
--Armin
Received on Tue Aug 08 2000 - 13:26:00 NZST