Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755693AbZLYRJy (ORCPT ); Fri, 25 Dec 2009 12:09:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756333AbZLYRJx (ORCPT ); Fri, 25 Dec 2009 12:09:53 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:42783 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756180AbZLYRJw (ORCPT ); Fri, 25 Dec 2009 12:09:52 -0500 Date: Fri, 25 Dec 2009 18:09:44 +0100 From: Pavel Machek To: Alan Stern Cc: Linus Torvalds , "Rafael J. Wysocki" , Zhang Rui , LKML , ACPI Devel Maling List , pm list Subject: Re: Async resume patch (was: Re: [GIT PULL] PM updates for 2.6.33) Message-ID: <20091225170943.GB1581@ucw.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1526 Lines: 31 Hi! > > That's partly why I realy did suggest that we do the async stuff purely in > > the USB layer, rather than try to put it deeper in the device layer. And > > if we do support it "natively" in the device layer like Rafael's latest > > patch, I still think we should be very very nervous about making devices > > async unless there is a measured - and very noticeable - advantage. > > Agreed. Arjan's measurements indicated that USB was one of the biggest > offenders; everything else other than the PS/2 mouse was much faster. > Given these results there isn't much incentive to do anything else > asynchronously. > > (However other devices not present on Arjan's machine may be a > different story. Spinning up multiple external disks is a good example > -- although here it may be necessary for the driver to take charge, > because spinning up a disk requires a lot of power and doing too many > of them at the same time could be bad.) Well, system would better be able to supply enough current... because usb disks auto-sleep on their own, and then something like async ls -l /*/* would kill your machine... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/