From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262347AbTEEPeC (ORCPT ); Mon, 5 May 2003 11:34:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262349AbTEEPeC (ORCPT ); Mon, 5 May 2003 11:34:02 -0400 Received: from mail.ithnet.com ([217.64.64.8]:53009 "HELO heather.ithnet.com") by vger.kernel.org with SMTP id S262347AbTEEPeB (ORCPT ); Mon, 5 May 2003 11:34:01 -0400 Date: Mon, 5 May 2003 17:32:49 +0200 From: Stephan von Krawczynski To: Karsten Keil Cc: alan@lxorguk.ukuu.org.uk, kai@tp1.ruhr-uni-bochum.de, linux-kernel@vger.kernel.org Subject: Re: ISDN massive packet drops while DVD burn/verify Message-Id: <20030505173249.50a72df9.skraw@ithnet.com> In-Reply-To: <20030505142300.GC28010@pingi3.kke.suse.de> References: <20030416151221.71d099ba.skraw@ithnet.com> <20030419193848.0811bd90.skraw@ithnet.com> <1050789691.3955.17.camel@dhcp22.swansea.linux.org.uk> <20030505142300.GC28010@pingi3.kke.suse.de> Organization: ith Kommunikationstechnik GmbH X-Mailer: Sylpheed version 0.8.11 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 5 May 2003 16:23:00 +0200 Karsten Keil wrote: > Hi Stephan, Hi Karsten, long time no hear ;-) > > Sorry Alan, "been there, done that" > > I made ISDN work on just about anything that you would call an OS on > > sometimes quite ancient hardware (compared to nowadays), and I really > > cannot imagine that the combined (though sometimes confusing) efforts of > > you, Andre, Pavel, name-one on IDE made a dual 1.4 GHz PIII slower > > (responding) than a M68k 7,14 MHz with a polling IDE interface - which > > happens to be the slowest thing I ever did ISDN programming on > > _flawlessly_. > > > > No Alan and Kai are right. > > The problem with the Infineon ISDN chips is that the fifos are small and so > IRQ latency is relativ critical. 32 or 64 bytes are only 4/8 ms, and if one > of these 32 Byte is dropped, the complete frame is lost. Modern ethernet > cards allways have fifos for multiple complete frames, so that such things > don't happen here. I know the relatively small fifos. On the other hand compared to the ridiculous throughput of 8 kByte/sec (single channel) (which most people seem to ignore in this discussion), it is ok. Let me simply ask back: is the IDE code in nowadays 2.4 kernel so bad, that a dual 1,4 GHz PIII cpu with 3 GB ram performs much worse than a 90 MHz P I with 64 MB and OS/2 on it??? _My_ isdn drivers showed _no_ such problems under OS/2 and IDE load... How did we manage to become that bad? > You can try to use HFC based ISDN cards (e.g. Conrad: ISDN TA 128K) the > fifos are much bigger (7.5kB) so at least 4 complete 1500 byte frames can be > handled without segmentation. That increase the IRQ latency a lot (~900 ms). I know HFC is nice. But that cannot mean ISAC/HSCX must have dropouts. You have to have long interrupt lock outs for such a behaviour, which cannot be intended at all. -- Regards, Stephan