From nobody Thu Jan 13 16:26:19 2022 X-Original-To: net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 430B71948AB5 for ; Thu, 13 Jan 2022 16:26:22 +0000 (UTC) (envelope-from glebius@freebsd.org) Received: from cell.glebi.us (glebi.us [162.251.186.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "cell.glebi.us", Issuer "cell.glebi.us" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4JZVDZ08dSz4THy for ; Thu, 13 Jan 2022 16:26:21 +0000 (UTC) (envelope-from glebius@freebsd.org) Received: from cell.glebi.us (localhost [127.0.0.1]) by cell.glebi.us (8.16.1/8.16.1) with ESMTPS id 20DGQJ0W072239 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 13 Jan 2022 08:26:19 -0800 (PST) (envelope-from glebius@freebsd.org) Received: (from glebius@localhost) by cell.glebi.us (8.16.1/8.16.1/Submit) id 20DGQJZO072238; Thu, 13 Jan 2022 08:26:19 -0800 (PST) (envelope-from glebius@freebsd.org) X-Authentication-Warning: cell.glebi.us: glebius set sender to glebius@freebsd.org using -f Date: Thu, 13 Jan 2022 08:26:19 -0800 From: Gleb Smirnoff To: George Neville-Neil Cc: net@freebsd.org Subject: Re: compressed TIME-WAIT to be decomissioned Message-ID: References: List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4JZVDZ08dSz4THy X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-ThisMailContainsUnwantedMimeParts: N On Wed, Jan 12, 2022 at 05:01:51PM -0500, George Neville-Neil wrote: G> > * Who told that 2*MSL (60 seconds) is adequate time to keep TIME-WAIT? G> > In 71d2d5adfe1 I added some stats on usage of tcptw and experimented a bit G> > with lowering net.inet.tcp.msl. It appeared that lowering it down three G> > times doesn't have statistically significant effect on TIME-WAIT use stats. G> > This means that the already miniscule number of TIME-WAIT connection on a G> > modern HTTP server can be lowered 3 times more. Feel free to lower G> > net.inet.tcp.msl and do your own measurements with G> > 'netstat -sp tcp | grep TIME-WAIT'. I'd be glad to see your results. G> G> The origin of the 2*MSL is pretty old and from a different type of network, but, my understanding of your proposal is not a change to this value anyway, is that correct? The removal of tcptw is a separate issue, if I understand you correctly. Right. I'm not suggesting to change default MSL in FreeBSD. Just saying that my experiments shown that it can be divided down by three with no effects. And those people who are really concerned with amount of TIME-WAITs hanging around can do that on their machines. As you say "2*MSL is pretty old and from a different type of network", so it probably can be reconsidered. But that's a separate thing to discuss. -- Gleb Smirnoff