Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750862AbWCIKFm (ORCPT ); Thu, 9 Mar 2006 05:05:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750918AbWCIKFm (ORCPT ); Thu, 9 Mar 2006 05:05:42 -0500 Received: from jaguar.mkp.net ([192.139.46.146]:57751 "EHLO jaguar.mkp.net") by vger.kernel.org with ESMTP id S1750845AbWCIKFl (ORCPT ); Thu, 9 Mar 2006 05:05:41 -0500 To: Paul Mackerras Cc: Jesse Barnes , Linus Torvalds , akpm@osdl.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, Alan Cox , linuxppc64-dev@ozlabs.org Subject: Re: [PATCH] Document Linux's memory barriers [try #2] References: <17423.32792.500628.226831@cargo.ozlabs.ibm.com> <200603082034.00238.jbarnes@virtuousgeek.org> <17423.45681.476222.143773@cargo.ozlabs.ibm.com> From: Jes Sorensen Date: 09 Mar 2006 05:05:39 -0500 In-Reply-To: <17423.45681.476222.143773@cargo.ozlabs.ibm.com> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 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: 1284 Lines: 26 >>>>> "Paul" == Paul Mackerras writes: Paul> Jesse Barnes writes: >> So ultimately mmiowb() is the only thing drivers really have to >> care about on Altix (assuming they do DMA mapping correctly), and >> the rules for that are fairly simple. Then they can additionally >> use read_relaxed() to optimize performance a bit (quite a bit on >> big systems). Paul> If I can be sure that all the drivers we care about on PPC use Paul> mmiowb correctly, I can reduce or eliminate the barrier in Paul> write*, which would be nice. Paul> Which drivers have been audited to make sure they use mmiowb Paul> correctly? In particular, has the USB driver been audited? I think the primary drivers we've looked at are drivers/net/tg3.c, drivers/net/s2io.c, drivers/scsi/qla1280.c, and possibly the qla[234]xxx series - thats probably it! While we have USB on the systems, I don't think anyone has spend a lot of time verifying it in this context. At least the keyboard and mouse I have on this box seems to behave. Cheers, Jes - 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/