From owner-freebsd-performance@FreeBSD.ORG Wed Jul 16 22:42:45 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E54C137B401 for ; Wed, 16 Jul 2003 22:42:45 -0700 (PDT) Received: from puffin.mail.pas.earthlink.net (puffin.mail.pas.earthlink.net [207.217.120.139]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5617443F93 for ; Wed, 16 Jul 2003 22:42:45 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from user-uinj8ql.dialup.mindspring.com ([165.121.163.85] helo=mindspring.com) by puffin.mail.pas.earthlink.net with asmtp (SSLv3:RC4-MD5:128) (Exim 3.33 #1) id 19d1XD-0000lf-00; Wed, 16 Jul 2003 22:42:32 -0700 Message-ID: <3F16370C.674EE08D@mindspring.com> Date: Wed, 16 Jul 2003 22:41:32 -0700 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: James West References: <20030716125123.53307.qmail@mail.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-ELNK-Trace: b1a02af9316fbb217a47c185c03b154d40683398e744b8a4d1da5842b0fa92832ffe02efbbca9093350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c cc: freebsd-performance@freebsd.org Subject: Re: Major problem with "No buffer space available" errors X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Jul 2003 05:42:46 -0000 James West wrote: > I'm having huge problems with "No buffer space available" errors. I've > increased MAXUSERS to 512 in the kernel, recompiled, rebooted and the > sysctl values below show that everything is up'ed to the max. Historically, the most common cause of this message has been an interface you were actively feeding data going down. Most commonly, this occurs in the use of UDP and ICMP protocols (e.g. "ping") out a downed interface, since they are not constrained by your sendspace settings, which apply to TCP (they will basically permit you to use all your buffer in the attempt). So the questions to answer are: 1) Are you using a lot of ICMP (e.g. ping, traceroute, RIP, etc.)? 2) Are you using a lot of UDP (e.g. Linux NFS clients using UDP mounts and an rsize or wsize larger than the MTU would permit to fit in a single UDP packet)? Other than that, you should "netstat -an" and add up the contents of the SendQ/RecvQ columns. It's possible that, in fact, you *are* running out of buffer space. For the default of 64K, you would need 2G of RAM dedicated to nothing but mbufs (not including headers!) to support only 32,768 simultaneous connections without mbuf overcommit. Dropping the sndspace/rcvspace paramaters back to their pre-bump-up defaults will double the number of connections for the same amount of RAM. -- Terry