From owner-freebsd-questions@FreeBSD.ORG Wed Jul 6 16:49:54 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3B2EB106566B for ; Wed, 6 Jul 2011 16:49:54 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-gy0-f182.google.com (mail-gy0-f182.google.com [209.85.160.182]) by mx1.freebsd.org (Postfix) with ESMTP id EDF8F8FC12 for ; Wed, 6 Jul 2011 16:49:53 +0000 (UTC) Received: by gyf3 with SMTP id 3so76907gyf.13 for ; Wed, 06 Jul 2011 09:49:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; 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; bh=wWI9eMscC1XLzrTPEmedbTrWNHA1CNtlfDAJNQPzrbQ=; b=h1/o7xStsfnSJM8cdvS/gBhdUyIRwAfBtskxuqJyAjpO5tlKYwYfaRvDOgKPa5xOrR yZ4xTvhHylGFz5yVwHceNN6BnWWF7armrtC9V756hUyzKgN4RFmx1GOS+caeJT+Uo5LQ 0cwvmnTXtZEJwohTbdqBhB/tgiwuSLcifVR/g= MIME-Version: 1.0 Received: by 10.150.179.2 with SMTP id b2mr7152186ybf.410.1309969543074; Wed, 06 Jul 2011 09:25:43 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.151.45.11 with HTTP; Wed, 6 Jul 2011 09:25:43 -0700 (PDT) In-Reply-To: <4E147F54.40908@zedat.fu-berlin.de> References: <4E1421D9.7080808@zedat.fu-berlin.de> <4E147F54.40908@zedat.fu-berlin.de> Date: Thu, 7 Jul 2011 00:25:43 +0800 X-Google-Sender-Auth: 8nObOuO4iMSAsoX23760fo-XSf8 Message-ID: From: Adrian Chadd To: "O. Hartmann" Content-Type: text/plain; charset=ISO-8859-1 Cc: FreeBSD Current , arrowdodger <6yearold@gmail.com>, freebsd-questions@freebsd.org Subject: Re: Heavy I/O blocks FreeBSD box for several seconds X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Jul 2011 16:49:54 -0000 Has anyone re-run those IO benchmarks? Something smells fishy there.. (with the benchmarking.) adrian 2011/7/6 O. Hartmann : > On 07/06/11 12:37, arrowdodger wrote: >> >> 2011/7/6 O. Hartmann >> >>> When performing an update on the ports tree via "portsnap fetch update" >>> or >>> when checking out (or) large Subversion repositories or when copying >>> large >>> data files (~ 50 to 250 GB in size, results from numerical modelings) or >>> when compiling world, FreeBD 9.0 and FreeBSD 8.2-STABLE tend to "freeze" >>> for >>> several seconds or drop overall performance dramatically for seconds. On >>> boxes with only console- or terminal access (no GUI) a running 'vi' gets >>> stuck for seconds while one of the processes producing heavy I/O is >>> running, >>> or the output of a 'cat' of a large file stops for several seconds. >>> >>> Using X11, this phenomenon gets even worse and the 'freezing' tends to >>> persist sometimes for more than 10 or 15 seconds. >>> >> >> I've also had (and still having) this problem on FreeBSD 7.2-RELEASE and >> 8-STABLE with both UFS and ZFS. Though, i've been running FreeBSD not on >> powerful servers, but on laptops (2-core CPU's, 2 GB of RAM). But still, >> KDE4 on Linux performs much better during high disk IO. > > I read about issues with the old codebase of X11 in FreeBSD's ports used, > which could be the cause of some performance problems, but I wouldn't expect > those I/O-triggered blockings on boxes without any GUI. > > I saw Linux very often performing tremendously better when used as a > workstation or desktop, but this is often gained on the costs of other > subsystems. I followed a very hard-to-understand discussion about grouping > threads related to ttys which seems to get higher priorized in Linux to make > the GUI more fluent, but this is definitely on cost of other subsystems, > which in consequence gets less priorized. > But even without GUI, Linux seems to perform I/O much better on > multicore-/multiprocessor boxes than FreeBSD *.X and 9.X). > > Today I looked at some benchmarks performed by Phoronix/openbenchmark.org > (http://www.phoronix.com/scan.php?page=article&item=freebsd8_ubuntu910&num=9) > and it seems that threaded I/O is an issue in FreeBSD (compared to Linux). I > have no glue how to "tune" those bottlenecks away in FBSD. > > I use SCHED_ULE on all machines, since it is supposed to be performing > better on multicore boxes, but there are lots of suggestions switching back > to the old SCHED_4BSD scheduler. > > Oliver > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >