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To: hackers@freebsd.org
Subject: PPP input processing problem (slowness)
Date: Tue, 08 Jul 1997 16:20:19 -0400
From: Brian McGovern <bmcgover@cisco.com>
Sender: owner-hackers@freebsd.org
X-Loop: FreeBSD.org
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I'm having a bit of a problem with my device driver when receiving PPP
packets. I've taken a look at sio.c and read what I can find in the BSD
4.4 Implementation book (read - the Red Book), and I'm doing what I'm told
I'm supposed to do. Obviously, I'm missing something :) 

Transmitting packets work fine, as does character mode. The problem appears
in getting the system to process incoming packets.

Basically, in my interrupt handler, I do

EITHER
  move the bytes with b_to_q() to &tp->t_rawq
OR
  use l_rint to move the bytes, one at a time.
THEN
  call setsofttty(). I have no idea what this does, but the sio driver had it,
  so its here... :)
  call ttwakeup();

Also, based on what else happens during the interrupt cycle, wakeup(tp) and
ttwwakeup(tp) can also get called.

Any suggestions are welcome.
	-Brian