From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp2.linux-foundation.org (smtp2.linux-foundation.org [207.189.120.14]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "smtp.linux-foundation.org", Issuer "CA Cert Signing Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 089FADDDF8 for ; Fri, 24 Aug 2007 02:16:52 +1000 (EST) Date: Thu, 23 Aug 2007 09:16:42 -0700 (PDT) From: Linus Torvalds To: Nick Piggin Subject: Re: wmb vs mmiowb In-Reply-To: <20070823042038.GI18788@wotan.suse.de> Message-ID: References: <20070822045714.GD26374@wotan.suse.de> <200708221202.12403.jesse.barnes@intel.com> <20070823022043.GB18788@wotan.suse.de> <20070823042038.GI18788@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Cc: linux-ia64@vger.kernel.org, Jesse Barnes , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 23 Aug 2007, Nick Piggin wrote: > > Also, FWIW, there are some advantages of deferring the mmiowb thingy > until the point of unlock. And that is exactly what ppc64 does. But you're missing a big point: for 99.9% of all hardware, mmiowb() is a total no-op. So when you talk about "advantages", you're not talking about any *real* advantage, are you? Linus