From owner-cvs-all@FreeBSD.ORG Wed Aug 1 18:58:00 2007 Return-Path: Delivered-To: cvs-all@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C3E9C16A4E6; Wed, 1 Aug 2007 18:58:00 +0000 (UTC) (envelope-from gad@FreeBSD.org) Received: from smtp5.server.rpi.edu (smtp5.server.rpi.edu [128.113.2.225]) by mx1.freebsd.org (Postfix) with ESMTP id 84D0C13C46C; Wed, 1 Aug 2007 18:58:00 +0000 (UTC) (envelope-from gad@FreeBSD.org) Received: from [128.113.24.47] (gilead.netel.rpi.edu [128.113.24.47]) by smtp5.server.rpi.edu (8.13.1/8.13.1) with ESMTP id l71HvWQ9022546; Wed, 1 Aug 2007 13:57:33 -0400 Mime-Version: 1.0 Message-Id: In-Reply-To: <200707312211.l6VMBupO010347@repoman.freebsd.org> References: <200707312211.l6VMBupO010347@repoman.freebsd.org> Date: Wed, 1 Aug 2007 13:57:31 -0400 To: Peter Wemm , src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org From: Garance A Drosehn Content-Type: text/plain; charset="us-ascii" ; format="flowed" X-RPI-SA-Score: undef - spam scanning disabled X-CanItPRO-Stream: default X-Canit-Stats-ID: Bayes signature not available X-Scanned-By: CanIt (www . roaringpenguin . com) on 128.113.2.225 Cc: Subject: Re: cvs commit: src/sys/netinet tcp_subr.c tcp_timer.h X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Aug 2007 18:58:00 -0000 At 10:11 PM +0000 7/31/07, Peter Wemm wrote: > > The old behavior (with hz=100) caused the connection to typically > drop between 90 and 110 seconds of getting no response. > > Now boot with kern.hz=1000 (default). The same test causes the > ssh session to drop after just 9-10 seconds. This is a big deal > on a wifi connection. > > With kern.hz=1000, change sysctl net.inet.tcp.rexmit_min from 3 > to 30. Note how it behaves the same as when HZ was 100. Also, > note that when booting with hz=100, net.inet.tcp.rexmit_min > *used* to be 30. > As a workaround, to avoid rebooting or rebuilding a kernel, you > can run "sysctl net.inet.tcp.rexmit_min=30" and add > "net.inet.tcp.rexmit_min=30" to /etc/sysctl.conf. This is safe > to run from 6.0 onwards. Oh man, this is extremely excellent. I have a chat server I run, and when I tried to upgrade that machine from 4.x to 6.x last year, it started seeing a lot of dropped connections. At the time I did a panic fallback to running 5.x instead, which worked okay enough. I just made a second attempt at upgrading to the latest 6.x on last Monday (9 days ago), and once again the server has been dropping connections much more often than it should. But still, it only drops about 50 connections a day (out of maybe a thousand), and I didn't have the slightest idea how I could track the problem down. Checking sysctls, the old server does have tcp.rexmit_min=30 while the new one has it at 3. If changing that back to 30 will solve the problem with dropped connections, it will be great! I really don't want to be forced back to 5.x yet again! -- Garance Alistair Drosehn = drosehn@rpi.edu Senior Systems Programmer or gad@FreeBSD.org Rensselaer Polytechnic Institute; Troy, NY; USA