Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753480AbXIRVCU (ORCPT ); Tue, 18 Sep 2007 17:02:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751159AbXIRVCI (ORCPT ); Tue, 18 Sep 2007 17:02:08 -0400 Received: from an-out-0708.google.com ([209.85.132.240]:50526 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751088AbXIRVCH (ORCPT ); Tue, 18 Sep 2007 17:02:07 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=kaaaj5v7WnN9VIIV+Z2pE5uY7at7YgC2aCqK7f/LyZ4qvGCrjXt5W85yMm5MN2KdtLchiPM7ovGm3NvWKkY/GNRZjZ9ZWoWSMncvtbpxNF89A7K4BCY8q//69KvbRNZu1ylfrktv2RRF2oipKxVU/rrm6VfNMOcbR4/XGAKLQn4= Message-ID: <43e72e890709181402x7335d0acp306cf576fac6c070@mail.gmail.com> Date: Tue, 18 Sep 2007 17:02:06 -0400 From: "Luis R. Rodriguez" To: "Linus Torvalds" Subject: Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices Cc: "Alan Cox" , linux-kernel , "Jeff Garzik" , "John W. Linville" , linux-wireless In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <43e72e890709171322x76ab6b70xd29bf97e3643c553@mail.gmail.com> <20070918113401.6a8a737f@the-village.bc.nu> <43e72e890709181146s604e0f9fl8b0c16627469c77f@mail.gmail.com> <43e72e890709181207j7c85dc29sb355a9f5a4207411@mail.gmail.com> <43e72e890709181312sf2b421cn49be3389b3786a2a@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1122 Lines: 27 On 9/18/07, Linus Torvalds wrote: > > > On Tue, 18 Sep 2007, Luis R. Rodriguez wrote: > > > > An extra branch is created on MMIO-only devices on read/writes on the > > IO_COND macro using this interface -- or is this optimized out? > > Umm. Does anybody actually have any performance numbers? > > The thing is, those things are *cheap* compared to the IO. And any > high-performance device will be using DMA for the real IO, so we're not > generally even talking about any performance-critical stuff. ACK but do we really need to benchmark this if we *know* we are creating unnecessary branches? How about Jeff's suggestion of introducing pci_mmio_map() ? This way we leave the current documenation as it is and just introduce this for MMIO-only devices. No benchmarks are necessary then, and no need to confuse people with the old API. Luis - 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/