Date: Mon, 18 Oct 2010 21:51:25 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: David Naylor <naylor.b.david@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: geom_sched usage Message-ID: <20101018195125.GA46115@onelab2.iet.unipi.it> In-Reply-To: <201010180943.37042.naylor.b.david@gmail.com> References: <201010180943.37042.naylor.b.david@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20101018195125.GA46115>