From owner-freebsd-current@FreeBSD.ORG Mon Oct 18 19:57:08 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 245481065670 for ; Mon, 18 Oct 2010 19:57:08 +0000 (UTC) (envelope-from luigi@onelab2.iet.unipi.it) Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.59.238]) by mx1.freebsd.org (Postfix) with ESMTP id D93DC8FC28 for ; Mon, 18 Oct 2010 19:57:07 +0000 (UTC) Received: by onelab2.iet.unipi.it (Postfix, from userid 275) id 1FF2673098; Mon, 18 Oct 2010 21:51:25 +0200 (CEST) Date: Mon, 18 Oct 2010 21:51:25 +0200 From: Luigi Rizzo To: David Naylor Message-ID: <20101018195125.GA46115@onelab2.iet.unipi.it> References: <201010180943.37042.naylor.b.david@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201010180943.37042.naylor.b.david@gmail.com> User-Agent: Mutt/1.4.2.3i Cc: freebsd-current@freebsd.org Subject: Re: geom_sched usage X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Oct 2010 19:57:08 -0000 On Mon, Oct 18, 2010 at 09:43:28AM +0200, David Naylor wrote: > Hi, > > I've used geom_sched to some success. Normally I do not notice anything but > today I was copying big files over a gigabit ethernet and my laptop was not > very responsive. I loaded gsched and the responsiveness improved (although > still rather bad for anything requiring something from the HDD). > > Thank you for all this work :-) > > Some questions I have: > > - with a gmirror should the gsched be attached to the underlying devices (aka > /dev/ad?) or to the mirror device (aka /dev/mirror/?)? always attach as close as possible to the hardware. > - is there anyway to automatically attach gsched to a device on startup (i.e. > in rc.conf)? no, you have to build some script yourself. > > - is there a way to prioritise random IO (vs sequential reads from big > files)? no way to do that, but you can modify the quantum size and time to let sequential reads get shorter chunks kern.geom.sched.rr.quantum_kb: 8192 kern.geom.sched.rr.quantum_ms: 100 kern.geom.sched.rr.wait_ms: 10 e.g. on a laptop it might make sense to set quantum_ms=50 and quantum_kb=2048 > - gsched_as does not appear to be installed. true, gsched_as was just a proof of concept and gsched_rr includes anticipation and round robin, so it is a superset of gsched_as cheers luigi