Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753055Ab0FWTIR (ORCPT ); Wed, 23 Jun 2010 15:08:17 -0400 Received: from bar.sig21.net ([80.81.252.164]:54280 "EHLO bar.sig21.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751708Ab0FWTIQ (ORCPT ); Wed, 23 Jun 2010 15:08:16 -0400 Date: Wed, 23 Jun 2010 21:07:43 +0200 From: Johannes Stezenbach To: "Luis R. Rodriguez" Cc: Matthew Garrett , Jussi Kivilinna , Maxim Levitsky , David Quan , Bob Copeland , "Luis R. Rodriguez" , ath5k-devel@venema.h4ckr.net, linux-wireless@vger.kernel.org, linux-kernel , Jonathan May , Tim Gardner Subject: Re: [ath5k-devel] [PATCH v2] ath5k: disable ASPM Message-ID: <20100623190743.GA22855@sig21.net> References: <20100622172545.GA22680@srcf.ucam.org> <20100622175058.GA23499@srcf.ucam.org> <20100622184426.GA24546@srcf.ucam.org> <20100622193143.GA17803@sig21.net> <20100623143940.GA5424@sig21.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-Spam-21-Score: -3.6 (---) X-Spam-21-Report: No, score=-3.6 required=5.0 tests=ALL_TRUSTED=-1.8,AWL=0.764,BAYES_00=-2.599 autolearn=no Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1618 Lines: 39 On Wed, Jun 23, 2010 at 09:28:57AM -0700, Luis R. Rodriguez wrote: > On Wed, Jun 23, 2010 at 7:39 AM, Johannes Stezenbach wrote: > > > > If enabling ASPM comes with a performance penalty (which is not unexpected, > > there is usually a tradeoff between performance and power consumption), > > do you think a boot time option (pcie_aspm=) or compile time option > > (CONFIG_PCIEASPM) is the right user interface? > > > > > > But meanwhile I found that CONFIG_PCIEASPM has a runtime > > interface, /sys/module/pcie_aspm/parameters/policy. > > http://lwn.net/Articles/266585/ > > Same thing, its to be used by developers not users, damn it we should > just remove this crap. Hopefully I got at least the message across that there is a good reason to have an interface where the user can select the ASPM policy? If your answer is "reboot and change the BIOS setting" then you didn't get what I was talking about _at all_. Also, having now briefly looked at pcie/aspm.c, I do not share your opinion that it is crap, except maybe for the force enable. If I read it correctly it will by default keep the BIOS settings, but offers a per-device sysfs attribute to change the ASPM link state, and it seems to do sanity checking, and takes care that both ends of the link agree. (disclaimer: I haven't tested any of it, only briefly looked at the code) Johannes -- 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/