From owner-freebsd-performance@FreeBSD.ORG Wed Sep 30 06:30:35 2009 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id BD0AD1065696 for ; Wed, 30 Sep 2009 06:30:35 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from mail-fx0-f222.google.com (mail-fx0-f222.google.com [209.85.220.222]) by mx1.freebsd.org (Postfix) with ESMTP id 4DD0C8FC0A for ; Wed, 30 Sep 2009 06:30:34 +0000 (UTC) Received: by fxm22 with SMTP id 22so1576826fxm.36 for ; Tue, 29 Sep 2009 23:30:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type; bh=wF2kj6Wc5n97dd4B4WR5PibbTfB70Gk3lMsO88WyQeU=; b=f25Cvczjif1reahWtulu4qR/xPEzV/522S/RDO1imSzQo0kePsW6uITmQh30GtzYYN vtY3s7qsW9OAJgfBBcju5TJQuTmO5WXS8JmM63l9eYACGd2qwzwtpI+N1ykBvMZyyOO6 nFTc2t9S0pXAWU6Ymv0LCMKlrkaUYUMMeG1Cc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=aAFAu/InCf3hhkahIrj5I56IHq+c5hfYKku2ovkWzaoCNJwWpZLaUhd7hEOHBkINb0 3n57/HrtltBh2IrN0QP+pfNWYBcv9lAo2ZZ6F9WS+JY2hkqqHIMBCQqEy8rTapHe9FNR RoNChZNTlzz9MA/GAKAx1VYdruSmgqGkDF0u8= MIME-Version: 1.0 Sender: asmrookie@gmail.com Received: by 10.223.76.65 with SMTP id b1mr1396168fak.44.1254292234177; Tue, 29 Sep 2009 23:30:34 -0700 (PDT) In-Reply-To: <200909300226.CAA29195@sopwith.solgatos.com> References: <200909300226.CAA29195@sopwith.solgatos.com> Date: Wed, 30 Sep 2009 08:30:34 +0200 X-Google-Sender-Auth: 66023eafc74084c1 Message-ID: <3bbf2fe10909292330t753bcad1r69ae67d7e898ee35@mail.gmail.com> From: Attilio Rao To: Dieter Content-Type: text/plain; charset=UTF-8 Cc: freebsd-performance@freebsd.org Subject: Re: A specific example of a disk i/o problem (was: FreeBSD vs Ubuntu) X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Sep 2009 06:30:35 -0000 2009/9/30 Dieter : >> > My question is why is FreeBSD's disk i/o performance so bad? >> >> As I mentioned... this was discussed actively in slashdot. You will find >> there many good comments on this. > > All I saw in slashdot was a ffs vs ext comment. I don't believe the problems > I'm seeing are filesystem related. > >> > Not just in the benchmarks with debugging on, but in real world usage >> > where it actually matters. >> >> Are you saying this from actual experience or from reading other people's >> comments? > > Here is a specific demo of one disk i/o problem I'm seeing. Should be > easy to reproduce? > > http://lists.freebsd.org/pipermail/freebsd-performance/2008-July/003533.html > > This was over a year ago, so add 7.1 to the list of versions with the problem. > I believe that the > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 1148109, size: 4096 > messages I'm getting are the same problem. A user process is hogging > the bottleneck (disk buffer cache?) and the swapper/pager is getting starved. Sorry, do you have a PR/describing e-mail with this issue? Can you be a bit more precise? The problem reported in the earlier post, however, is interesting and worths more analysis. More speficially, would you be interested in reproducing and playing a bit with some diagnostic tool/configurations I can point you at? Attilio -- Peace can only be achieved by understanding - A. Einstein