From owner-freebsd-questions@FreeBSD.ORG Mon Apr 25 20:24:11 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 0CD5A106566C for ; Mon, 25 Apr 2011 20:24:11 +0000 (UTC) (envelope-from kraduk@gmail.com) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 918498FC17 for ; Mon, 25 Apr 2011 20:24:10 +0000 (UTC) Received: by wyf23 with SMTP id 23so2385723wyf.13 for ; Mon, 25 Apr 2011 13:24:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=5VAhS779wqXjK28+6A68G94Mz62T4AZDzSklJ5azuM0=; b=Ikg2fq9PqYQtKAfLafeEo/qUJ/IoZwWNkrwmbmY16eYgYmQOO+4xtRMG6EEmSwjhKW RjymHtEVcwyHnnLfweOA72npRz9h4RDbGiKTzHyZ5sfUGjoc3URki7Wz/0fo5KAxgnTx 1TwIolWXHbEXCW+HiuoyFNTSKACulwM1pOqmQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=x1HZZDUGnNl2JMEENum2ToO4by7Tn71xFb9fk7Fq14favp+XVSkIKHvSKqclJFFB1Y ge3pDyU1QHdR13Ovp+EpJAfxpnS7/2E/E2MYwD1l0IzGXFC8IFOujCUWJzmGFo0B9fEy /fay4v9MV+sXtT07XMlCiVynniX2c0WzDySyc= MIME-Version: 1.0 Received: by 10.216.143.74 with SMTP id k52mr4078308wej.0.1303763049489; Mon, 25 Apr 2011 13:24:09 -0700 (PDT) Received: by 10.216.15.73 with HTTP; Mon, 25 Apr 2011 13:24:09 -0700 (PDT) In-Reply-To: <1303662094.42253.4.camel@z6000.lenzicasa> References: <1303662094.42253.4.camel@z6000.lenzicasa> Date: Mon, 25 Apr 2011 21:24:09 +0100 Message-ID: From: krad To: Sergio de Almeida Lenzi Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-questions@freebsd.org Subject: Re: ZFS performance strangeness 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: Mon, 25 Apr 2011 20:24:11 -0000 On 24 April 2011 17:21, Sergio de Almeida Lenzi wro= te: > Em Ter, 2011-04-12 =E0s 13:33 +0200, Lars Wilke escreveu: > > > Hi, > > > > There are quite a few threads about ZFS and performance difficulties, > > but i did not find anything that really helped :) > > Therefor any advice would be highly appreciated. > > I started to use ZFS with 8.1R, only tuning i did was setting > > > > vm.kmem_size_scale=3D"1" > > vfs.zfs.arc_max=3D"40000M" > > For me I solved the ZFS performace in FreeBSD and postgres databases > (about 100GB size) > by tunning vm.kmem_size to atout 3/4 of the ram size... > in your case, vm.kmem_size=3D(48 *3/4)=3D36G, it puts almost all the > database > in memory and it is now lightning fast... > I use to disable prefetch in zfs.. too > > Hope this can help, > > Sergio > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > wouldnt it be better to allow the db to use the memory rather than zfs, as this would involve far less context switches?