Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263915AbTIIOyF (ORCPT ); Tue, 9 Sep 2003 10:54:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263666AbTIIOyF (ORCPT ); Tue, 9 Sep 2003 10:54:05 -0400 Received: from mail.cs.tu-berlin.de ([130.149.17.13]:1187 "EHLO mail.cs.tu-berlin.de") by vger.kernel.org with ESMTP id S264170AbTIIOx6 (ORCPT ); Tue, 9 Sep 2003 10:53:58 -0400 Date: Tue, 9 Sep 2003 16:49:06 +0200 (MEST) From: Peter Daum Reply-To: Peter Daum To: Manfred Spraul cc: Jeff Garzik , Jamie Lokier , Adrian Bunk , Subject: Re: [2.4 patch] fix CONFIG_X86_L1_CACHE_SHIFT In-Reply-To: <3F5CDC65.6060409@colorfullife.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2242 Lines: 45 On Mon, 8 Sep 2003, Manfred Spraul wrote: > Context: Peter experiences very bad network performance with 2.4.22 - it > looks like 99% packet drop or something like that. The packet drop > disappears if CONFIG_L1_CACHE_SHIFT is set to 7 (i.e. 128 byte cache > line size). 2.4.21 works. > The network cards are some kind of atm cards. Several systems are > affected - at least Pentium II and PPro systems. > > Peter: what's the exact brand and nic driver that you use? Could you try > to figure out what exactly breaks? I'd use "ping -f -s 1500", perhaps > together with "tcpdump -s 1500 -x" on both ends. Meanwhile, I could verify that the problems do not occur, when I use an ethernet network adapter. All the machines have Marconi/Fore Systems Forerunner LE ATM cards (/proc/pci: ATM network controller: Integrated Device Tech IDT77211 ATM Adapter (rev 3)) with LAN emulation. To figure out what exactly breaks, is the hard part: There is no general malfunction, I only found some particular test cases. The easiest of these is: "wget ftp://ftp.nai.com/pub/datfiles/english/dat-4291.zip". With a vanilla 2.4.22 kernel, the data connection dies with a timeout after transferring some kbytes. When capturing the connection with tcpdump, the only thing unusual I can discover is that the time interval between 2 data packets coming in is unusually hight. I don't have the slightest idea, what is really going wrong. Transferring data from some other ftp server (e.g. ftp.kernel.org) works as usual. As esoterical as it sounds, the whole issue is 100% reproducible and disappears with CONFIG_L1_CACHE_SHIFT set to 7. (The example with wget is only the easiest test I could find - for my purposes, the fact that sendmail and samba don't work correctly makes the kernel almost useless). "Ping" doesn't show anything unusual (no dropped packets). Since the problem did not occur with older kernels, the "CONFIG_L1_CACHE_SHIFT" setting can hardly be the real problem. Regards, Peter - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/