Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 12 Dec 2002 14:10:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 12 Dec 2002 14:10:59 -0500 Received: from host136-27.pool217141.interbusiness.it ([217.141.27.136]:14606 "EHLO mdvsrvsmtp01.north.h3g.it") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Thu, 12 Dec 2002 14:10:57 -0500 X-MimeOLE: Produced By Microsoft Exchange V6.0.5762.3 Content-Class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Subject: Kernel bug handling TCP_RTO_MAX? Date: Thu, 12 Dec 2002 20:15:42 +0100 Message-ID: <047ACC5B9A00D741927A4A32E7D01B73D66176@RMEXC01.h3g.it> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Kernel bug handling TCP_RTO_MAX? thread-index: AcKiEsQqYuHs0uDZQieYDM6iK+0WiQ== From: "Andreani Stefano" To: , X-OriginalArrivalTime: 12 Dec 2002 19:15:42.0468 (UTC) FILETIME=[DD3D2C40:01C2A212] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 34 Problem: I need to change the max value of the TCP retransmission timeout. Background: According to Karn's exponential backoff algorithm, when the receiver doesn't acknowledge packets for a while, the sender should retransmit the latest not acknowledged packet several times increasing the delay (RTO) since this delay reaches the Max Retransmission Timeout Value. Testing environment: Red Hat Linux release 7.2 (Enigma), Kernel 2.4.7-10 on an i686, Kernel 2.4.7-10. Test details: I supposed this timeout in Linux was TCP_RTO_MAX, so I changed in /include/net/tcp.h the following line: #define TCP_RTO_MAX ((unsigned)(6*HZ)) //It was: ((unsigned)(120*HZ)) Then I recompiled the kernel, rebooted the machine and tested the solution. The result I obtained was the same I had before this modification. I'm confident there isn't an error in the testing procedure because I already tested with a Solaris server the same procedure (changing the tcp_rexmit_interval_max variable) and it works. I'm just trying to reproduce the modification of that parameter in Linux. Could it be a bug on the RTO calculation algorithm, or there is something I mistook? This is the first time I get into the linux kernel, so please be patient! Thanks, Stefano. ------------------------------- Stefano Andreani Freelance ICT Consultant H3G IOT Team - Italy tel. +39 347 8215965 stefano.andreani.ap@h3g.it - 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/