From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [203.10.76.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.ozlabs.org", Issuer "CA Cert Signing Authority" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id 947C8B7108 for ; Fri, 3 Jul 2009 08:41:20 +1000 (EST) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E847CDDD04 for ; Fri, 3 Jul 2009 08:41:19 +1000 (EST) Subject: Re: Preemption question (4xx related) From: Benjamin Herrenschmidt To: Josh Boyer In-Reply-To: <20090702111246.GG6189@zod.rchland.ibm.com> References: <24271342.post@talk.nabble.com> <1246486393.14483.14.camel@pasglop> <20090702001450.GF6189@zod.rchland.ibm.com> <1246519992.7551.1.camel@pasglop> <20090702111246.GG6189@zod.rchland.ibm.com> Content-Type: text/plain Date: Fri, 03 Jul 2009 08:41:00 +1000 Message-Id: <1246574460.7551.6.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Felix Radensky List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2009-07-02 at 07:12 -0400, Josh Boyer wrote: > On Thu, Jul 02, 2009 at 05:33:12PM +1000, Benjamin Herrenschmidt wrote: > >On Wed, 2009-07-01 at 20:14 -0400, Josh Boyer wrote: > > > >> I've toyed with that idea myself. I keep coming back to the fact that you need > >> a workload that would really leverage it, and I don't have one at the moment. > > > >To some extent that's true but just turning full preemption including > >kernel side with all the associated debug bits and lockdep should make a > >whole bunch of things show up even with ordinary workloads. > > I can look at doing that for ppc44x_defconfig. I'll be honest and say I don't > expect it to go well, particularly with lockdep :). > > >For 440 tend to boot an ubuntu distro off NFS root with all X & DRI 3D > >etc... and then run compiz :-) > > Yes. Because that's a totally realistic workload for a 440. I'm surprised you > don't have a p595 machine acting as your home router too! ;) It doesn't need to be realistic. In fact, a "realistic" workload is the worst thing to test with because it won't exercise all the "uncommon" code path which are the ones likely to bite. So yesm it's not a "realistic" workload, but it's a good "torture" workload to find bugs. Cheers, Ben.