From owner-freebsd-performance@FreeBSD.ORG Thu Sep 4 15:41:57 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 9F23A16A4BF for ; Thu, 4 Sep 2003 15:41:57 -0700 (PDT) Received: from perrin.nxad.com (internal.nxad.com [69.1.70.251]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1F69A43FB1 for ; Thu, 4 Sep 2003 15:41:57 -0700 (PDT) (envelope-from sean@nxad.com) Received: by perrin.nxad.com (Postfix, from userid 1001) id 722CA20F00; Thu, 4 Sep 2003 15:41:56 -0700 (PDT) Date: Thu, 4 Sep 2003 15:41:56 -0700 From: Sean Chittenden To: "Jim C. Nasby" Message-ID: <20030904224156.GD75041@perrin.nxad.com> References: <20030904220709.GR37152@nasby.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030904220709.GR37152@nasby.net> X-PGP-Key: finger seanc@FreeBSD.org X-PGP-Fingerprint: 3849 3760 1AFE 7B17 11A0 83A6 DD99 E31F BC84 B341 X-Web-Homepage: http://sean.chittenden.org/ User-Agent: Mutt/1.5.4i cc: freebsd-performance@FreeBSD.ORG Subject: Re: Best disk caching method (and PGSQL performance) 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, 04 Sep 2003 22:41:57 -0000 > If that's indeed the case, then it seems like the only way to get a > decent amount of data caching is by increasing the buffer size > (which apparently means increasing kern.nbuf, which also means > increasing KVA_PAGES (though I'm not at all sure about this). You can increase kern.nbuf and even have kern.nbuf available as a sysctl if you apply the following patch: http://people.freebsd.org/~seanc/patches/patch-HEAD-kern.nbuf One piece of advice I have received is, "I use an nbuf of something like twice the default one, and a BKVASIZE of 4 times the default. vfs.maxbufspace ends up at 445MB on the machine with 1GB, so it is maxed out now." As the sagely Mr. Bruce Evans has pointed out to me, buffer kva = nbuf * BKVASIZE, so it's not impossible to figure out what the nbuf level is for a machine, it is nice to not have to poke inside of header files to find the BKVASIZE. > Also, has anyone played with the other fsync options? FreeBSD only supports the default fsync option. -- Sean Chittenden