From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bos-spam.mrv.com (mx5.mrv.com [140.179.254.12]) by ozlabs.org (Postfix) with ESMTP id 901C7B7BBD for ; Tue, 29 Sep 2009 11:21:11 +1000 (EST) Date: Mon, 28 Sep 2009 18:21:06 -0700 From: Rex Feany To: Benjamin Herrenschmidt Subject: Re: [PATCH] powerpc/8xx: fix regression introduced by cache coherency rewrite Message-ID: <20090929012106.GA22798@compile2.chatsunix.int.mrv.com> References: <20090924004552.GA11737@compile2.chatsunix.int.mrv.com> <1253774659.7103.405.camel@pasglop> <20090924233346.GA445@compile2.chatsunix.int.mrv.com> <1253836376.7103.469.camel@pasglop> <20090925013528.GA2584@compile2.chatsunix.int.mrv.com> <1253843480.7103.492.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1253843480.7103.492.camel@pasglop> Cc: "linuxppc-dev@ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Thus spake Benjamin Herrenschmidt (benh@kernel.crashing.org): > On Thu, 2009-09-24 at 18:35 -0700, Rex Feany wrote: > > > > Then I can boot and get to a shell, but userspace is slow. 8 seconds > > to mount > > /proc (vs. less then a second using my old kernel)! Maybe this is an > > unrelated issue? I'm pretty clueless about the details, I'm sorry. > > PG_arch_1 is used to prevent a cache flush unless it is actually > > needed? > > Then why would changing the location of the tlbil_va() make a > > difference? > > I think there's more finishyness to 8xx than we thought. IE. That > tlbil_va might have more reasons to be there than what the comment > seems to advertize. Can you try to move it even higher up ? IE. > Unconditionally at the beginning of set_pte_filter ? > > Also, if that doesn't help, can you try putting one in > set_access_flags_filter() just below ? > > (Beware that there's two different versions of both functions, only the > first one is compiled/used on 8xx). > > It's going to be hard for me to get that "right" since I don't really > know what's going on with the core here, but I suppose if we get it > moving along with extra tlb invalidations, that should be "good enough" > until somebody who really knows what's going on comes up with possibly > a better fix. I've tried sticking tlbil_va() in those places, nothing seems to help. In some cases userspace is slow, in other cases userspace is faster and unstable: sometimes commands hang, sometimes I am able to ctrl-c and and kill it, sometimes I get other strange crashes or falures (so far no kernel oopses though). take care! /rex.