From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-in-01.arcor-online.net (mail-in-07.arcor-online.net [151.189.21.47]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.arcor.de", Issuer "Thawte Premium Server CA" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 923BB67B53 for ; Wed, 20 Sep 2006 05:11:45 +1000 (EST) In-Reply-To: <45103DF0.9050409@genesi-usa.com> References: <20060919222351.d27a1a06.sfr@canb.auug.org.au> <20060919182953.GK29167@austin.ibm.com> <20060919135259.303706d3.kim.phillips@freescale.com> <45103DF0.9050409@genesi-usa.com> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <9E674786-9AF3-4322-B642-7BAA58462B74@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [POWERPC] convert string i/o operations to C Date: Tue, 19 Sep 2006 21:10:34 +0200 To: Matt Sealey Cc: sfr@canb.auug.org.au, paulus@samba.org, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > For a generic "powerpc" kernel it can be understood, but when you > consider that on 970/POWER4 and above they use lwsync instead of sync lwsync (sync 1) doesn't (architecturally) do anything to order MMIO accesses, so you're misunderstanding something. > (google for them and see the mailing list posts :), just to breathe > back > some performance in spinlocks and so on, surely this can be > rejigged so > that processors don't do more work than necessary..? Even a noop takes > time doesn't it? No-ops don't matter for performance, compared to the cost of the I/O itself. It would help to avoid heavier-than-necessary synchronisation instructions if not needed on some certain CPU (or on non-SMP kernels, etc.) Segher