Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 13 Oct 1998 15:41:01 +1000
From:      Bruce Evans <bde@zeta.org.au>
To:        brian@Awfulhak.org, kjc@csl.sony.co.jp
Cc:        current@FreeBSD.ORG
Subject:   Re: Improper sharing of modem bandwidth
Message-ID:  <199810130541.PAA12787@godzilla.zeta.org.au>

next in thread | raw e-mail | index | archive | help
>Surely, once the packet queueing delay is reduced, we need to reduce
>the tty delay.   The current kernel doesn't have ioctls for the
>buffer size but slip uses a smaller tty buffer and has a better
>response time than ppp.

User ppp is behind a _lot_ of output buffering, including (at speeds >=
57600 Kbps) a 4KB tty buffer (up from 2KB in FreeBSD-2.2).  Perhaps the
increase from 2KB to 4KB is especially significant when the MTU is 1500.

Kernel ppp doesn't have this problem.  Kernel ppp also has a fast path
for incoming packets to avoid the average 5ms latency for polling the
pseudo-DMA input buffer.  This only seems to be important for local
connections.

Bruce

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199810130541.PAA12787>