Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992760AbWJUAjO (ORCPT ); Fri, 20 Oct 2006 20:39:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992758AbWJUAjN (ORCPT ); Fri, 20 Oct 2006 20:39:13 -0400 Received: from smtp.osdl.org ([65.172.181.4]:10158 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030366AbWJUAjM (ORCPT ); Fri, 20 Oct 2006 20:39:12 -0400 Date: Fri, 20 Oct 2006 17:38:32 -0700 (PDT) From: Linus Torvalds To: Ralf Baechle cc: David Miller , nickpiggin@yahoo.com.au, akpm@osdl.org, linux-kernel@vger.kernel.org, anemo@mba.ocn.ne.jp, linux-arch@vger.kernel.org, schwidefsky@de.ibm.com, James.Bottomley@SteelEye.com Subject: Re: [PATCH 1/3] Fix COW D-cache aliasing on fork In-Reply-To: <20061021000609.GA32701@linux-mips.org> Message-ID: References: <20061020214916.GA27810@linux-mips.org> <20061020.152247.111203913.davem@davemloft.net> <20061020225118.GA30965@linux-mips.org> <20061021000609.GA32701@linux-mips.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1358 Lines: 39 On Sat, 21 Oct 2006, Ralf Baechle wrote: > > > That said, maybe nobody does that. Virtual caches are a total braindamage > > in the first place, so hopefully they have limited use. > > On MIPS we never had pure virtual caches. Ok, so on MIPS my schenario doesn't matter. I think (but may be mistaken) that ARM _does_ have pure virtual caches with a process ID, but people have always ended up flushing them at context switch simply because it just causes too much trouble. Sparc? VIPT too? Davem? I have absolutely zero clue about s390. Anyway, it sounds to me like this is too big to decide for 2.6.19 anyway, and as far as I can tell this i snot a regression, right? Ie we've always had the aliasing issue. Ralf? But it would be good to have something for the early -rc1 sequence for 2.6.20, and maybe the MIPS COW D$ patches are it, if it has performance advantages on MIPS that can also be translated to other virtual cache users.. > Be sure I'm sending a CPU designers a strong message about aliases. Castration. That's the best solution. We don't want those people procreating. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/