From owner-freebsd-fs@FreeBSD.ORG Thu Mar 17 11:47:48 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 95061106566C for ; Thu, 17 Mar 2011 11:47:48 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-qw0-f54.google.com (mail-qw0-f54.google.com [209.85.216.54]) by mx1.freebsd.org (Postfix) with ESMTP id 469F18FC0C for ; Thu, 17 Mar 2011 11:47:47 +0000 (UTC) Received: by qwc9 with SMTP id 9so2176096qwc.13 for ; Thu, 17 Mar 2011 04:47:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:in-reply-to:references:from :date:x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; bh=aHXgDN9HMeB0w/3jbFCk7uLJpXCK+NQTACEcKtZcYic=; b=CQxVhppg2PICbeaRk9J+l4oWwoEuywex9xR9MW8favi/WmlykLkxMdP6f890EzdF/k bxc5ESdi+tORFPLkSJm7BM+k8AB95ftVeI6CbjTPv+rXHj+R5hKlrlJAtumo+YLfwtoc dc/BXcMYNK7rBGxPvvrFJ7CrkN5zf5Qku2OKU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=DYE4vsr6Xls80KoiDjeKor0Lvp5qewPh3Z3yl2LG17JR/ju/5YTnnlQxAZuKe3ZysV amzdmSoqECrOxmoW5tLj4igpmNR1nNgQmzTuvMbMeJjz5doFZ0UbS38VbsEoIkZ9YCYV nqXyAkF9phd14RWv4j6TVTWrKQSgTJftdtXEE= Received: by 10.229.111.225 with SMTP id t33mr971072qcp.61.1300360914093; Thu, 17 Mar 2011 04:21:54 -0700 (PDT) MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.229.78.193 with HTTP; Thu, 17 Mar 2011 04:21:14 -0700 (PDT) In-Reply-To: <20110317065720.GA49199@blazingdot.com> References: <4D7F7E33.7050103@yellowspace.net> <4D80BFB3.20706@yellowspace.net> <20110317065720.GA49199@blazingdot.com> From: Ivan Voras Date: Thu, 17 Mar 2011 12:21:14 +0100 X-Google-Sender-Auth: Bo5k6wDvX7P_8SbopHmAV3lbKio Message-ID: To: Marcus Reid Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-fs@freebsd.org Subject: Re: gmirror performance X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Mar 2011 11:47:48 -0000 On 17 March 2011 07:57, Marcus Reid wrote: > > Wow, that's great. =C2=A0I just almost doubled big sequential read perfor= mance > on one of my machines with this too. =C2=A0The question now is why the de= faults > are the way they are... =C2=A0Does a big vfs.read_max (described as "Clus= ter > read-ahead max block count") pessimize performance in some other way? Note that it will only help sequential reads. If you have a database, e-mail server or any other random IO load, it will not help you one bit. On the other hand, it will also not harm performance in that type of environments. It's an old tunable which has not been properly investigated ever since it was last modified 10 years ago; this and few other obscure file system tunables (hi/lo runningspace, dirhash_maxmem) will be much more sanely tuned for 9.0.