Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756102Ab1EDUyD (ORCPT ); Wed, 4 May 2011 16:54:03 -0400 Received: from mga09.intel.com ([134.134.136.24]:45538 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756004Ab1EDUx7 (ORCPT ); Wed, 4 May 2011 16:53:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.64,316,1301900400"; d="scan'208";a="638023472" Date: Wed, 4 May 2011 13:53:51 -0700 (Pacific Daylight Time) From: "Brandeburg, Jesse" To: Stephen Hemminger cc: David Miller , Sangtae Ha , Injong Rhee , "Valdis.Kletnieks@vt.edu" , "rdunlap@xenotime.net" , "lkml@techboom.com" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error In-Reply-To: <20110504130456.425dee68@nehalam> Message-ID: References: <20110504113351.4643a0c9@nehalam> <16668.1304537481@localhost> <20110504123738.7bb4d1ee@nehalam> <20110504.124053.260068550.davem@davemloft.net> <20110504130456.425dee68@nehalam> User-Agent: Alpine 2.00 (WNT 1167 2008-08-23) ReplyTo: "Brandeburg, Jesse" X-X-Sender: amrjbrandeb@imapmail.glb.intel.com MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1078 Lines: 27 On Wed, 4 May 2011, Stephen Hemminger wrote: > TCP Cubic keeps a metric that estimates the amount of delayed > acknowledgements to use in adjusting the window. If an abnormally > large number of packets are acknowledged at once, then the update > could wrap and reach zero. This kind of ACK could only > happen when there was a large window and huge number of > ACK's were lost. > > This patch limits the value of delayed ack ratio. The choice of 32 > is just a conservative value since normally it should be range of > 1 to 4 packets. > > Signed-off-by: Stephen Hemminger patch seems fine, but please credit the reporter (lkml@techboom.com) with reporting the issue with logs, maybe even with Reported-by: and some kind of reference to the panic message or the email thread in the text or header? -- 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/