Return-path: Received: from mail-iw0-f178.google.com ([209.85.223.178]:40530 "EHLO mail-iw0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754531AbZIKRnX (ORCPT ); Fri, 11 Sep 2009 13:43:23 -0400 Received: by iwn8 with SMTP id 8so549222iwn.4 for ; Fri, 11 Sep 2009 10:43:26 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1252632895-11914-1-git-send-email-lrodriguez@atheros.com> <1252632895-11914-4-git-send-email-lrodriguez@atheros.com> <40f31dec0909102316q7902098jbee7fd8d17c3f622@mail.gmail.com> <4AA9F22C.3090007@gmail.com> <43e72e890909110023k62a512bejd712a3449cc8328d@mail.gmail.com> From: "Luis R. Rodriguez" Date: Fri, 11 Sep 2009 10:43:06 -0700 Message-ID: <43e72e890909111043m78411058i86e61909a35412f@mail.gmail.com> Subject: Re: [PATCH 3/4] ath5k: define ath_common ops To: Linus Torvalds Cc: devel@driverdev.osuosl.org, ath9k-devel@venema.h4ckr.net, Jeff Garzik , linux-wireless@vger.kernel.org, Nick Kossifidis , Alan Cox Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Sep 11, 2009 at 7:24 AM, Linus Torvalds wrote: > > > On Fri, 11 Sep 2009, Luis R. Rodriguez wrote: >> >> That is the way I had it originally before submission, and I >> completely agree its reasonable to not incur additional cost at the >> expense of having two separate read/write paths, and perhaps we should >> only incur the extra cost on routines shared between >> ath9k/ath9k/ath9k_htc. But -- is there really is a measurable cost >> penalty? > > There's a measurable size penalty, at least. My tests so far yield no performance difference but I'm sure there is some, maybe as Jouni noted, more visible on embedded systems. > In fact, if you know what kind of IO op it is (ie "it's always MMIO"), > you'd be even better using "writel()" directly, Heh.. you realize I tried to document such a thing a while ago and it seems you opposed it [1]? [1] http://lkml.indiana.edu/hypermail/linux/kernel/0709.2/0593.html Luis