From owner-freebsd-current Mon Oct 12 22:41:40 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id WAA04925 for freebsd-current-outgoing; Mon, 12 Oct 1998 22:41:40 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.15.68.22]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id WAA04916 for ; Mon, 12 Oct 1998 22:41:36 -0700 (PDT) (envelope-from bde@godzilla.zeta.org.au) Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.7/8.8.7) id PAA12787; Tue, 13 Oct 1998 15:41:01 +1000 Date: Tue, 13 Oct 1998 15:41:01 +1000 From: Bruce Evans Message-Id: <199810130541.PAA12787@godzilla.zeta.org.au> To: brian@Awfulhak.org, kjc@csl.sony.co.jp Subject: Re: Improper sharing of modem bandwidth Cc: current@FreeBSD.ORG Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >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