From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [RFC PATCH net-next] tcp: introduce tcp_tw_interval to specifiy the time of TIME-WAIT Date: Fri, 28 Sep 2012 10:30:27 -0700 Message-ID: <5065DEB3.3040508@hp.com> References: <1348735261-29225-1-git-send-email-amwang@redhat.com> <20120927142334.GA3194@neilslaptop.think-freely.org> <1348813987.7264.41.camel@cr0> <20120928.024336.598451765169362800.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: amwang@redhat.com, nhorman@tuxdriver.com, netdev@vger.kernel.org, kuznet@ms2.inr.ac.ru, kaber@trash.net, edumazet@google.com To: David Miller Return-path: Received: from g4t0014.houston.hp.com ([15.201.24.17]:45491 "EHLO g4t0014.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758326Ab2I1Rae (ORCPT ); Fri, 28 Sep 2012 13:30:34 -0400 In-Reply-To: <20120928.024336.598451765169362800.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 09/27/2012 11:43 PM, David Miller wrote: > From: Cong Wang > Date: Fri, 28 Sep 2012 14:33:07 +0800 > >> I don't think reducing TIME_WAIT is a good idea either, but there must >> be some reason behind as several UNIX provides a microsecond-scale >> tuning interface, or maybe in non-recycle mode, their RTO is much less >> than 2*MSL? Microsecond? HP-UX uses milliseconds for the units of the tunable, though that does not necessarily mean it will actually be implemented to millisecond accuracy > Yes, there is a reason. It's there for retaining multi-million-dollar > customers. > > There is no other reasons these other systems provide these > facilities, they are simply there in an attempt to retain a dwindling > customer base. > > Any other belief is extremely naive. HP-UX's TIME_WAIT interval tunability goes back to HP-UX 11.0, which first shipped in 1997. It got it by virtue of using a "Mentat-based" stack which had that functionality. I may not have my history completely correct, but Solaris 2 also got their networking bits from Mentat, and I believe shipped before HP-UX 11. To my recollection, neither were faced with a dwindling customer base at the time. rick jones