From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964780AbXCAJtd (ORCPT ); Thu, 1 Mar 2007 04:49:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964783AbXCAJtd (ORCPT ); Thu, 1 Mar 2007 04:49:33 -0500 Received: from relay.2ka.mipt.ru ([194.85.82.65]:43387 "EHLO 2ka.mipt.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964780AbXCAJtc (ORCPT ); Thu, 1 Mar 2007 04:49:32 -0500 Date: Thu, 1 Mar 2007 12:47:23 +0300 From: Evgeniy Polyakov To: Pavel Machek Cc: Theodore Tso , Ingo Molnar , Linus Torvalds , Ulrich Drepper , linux-kernel@vger.kernel.org, Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Zach Brown , "David S. Miller" , Suparna Bhattacharya , Davide Libenzi , Jens Axboe , Thomas Gleixner Subject: Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3 Message-ID: <20070301094723.GJ7217@2ka.mipt.ru> References: <20070226172812.GC22454@2ka.mipt.ru> <20070226195416.GA11188@elte.hu> <20070227102832.GC23170@2ka.mipt.ru> <20070227115221.GJ8154@thunk.org> <20070227121116.GA31597@2ka.mipt.ru> <20070228161413.GA4319@ucw.cz> <20070301081808.GD7217@2ka.mipt.ru> <20070301092634.GB20171@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: <20070301092634.GB20171@elf.ucw.cz> User-Agent: Mutt/1.5.9i X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (2ka.mipt.ru [0.0.0.0]); Thu, 01 Mar 2007 12:48:28 +0300 (MSK) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 01, 2007 at 10:26:34AM +0100, Pavel Machek (pavel@ucw.cz) wrote: > > > 10% gain in speed is NOT worth major complexity increase. > > > > Should I create a patch to remove rb-tree implementation? > > If you can replace them with something simpler, and no worse than 10% > slower in worst case, then go ahead. (We actually tried to do that at > some point, only to realize that efence stresses vm subsystem in very > unexpected/unfriendly way). Agh, only 10% in the worst case. I think you can not even imagine what tricks network uses to get at least aditional 1% out of the box. Using such logic you can just abandon any further development, since it work as is right now. > > That practice is stupid IMO. > > Too bad. Now you can start Linux fork called Eugenix. > > (But really, Linux is not "maximum performance at any cost". Linux is > "how fast can we get that while keeping it maintainable?"). Should I read it like: we do not understand what it is and thus we do not want it? > That is why, while arguing syslets vs. kevents, you need need to argue > not "kevents are faster because they avoid context switch overhead", > but "kevents are _so much_ faster that it is worth the added > complexity". And Ingo seems to showing you they are not _so much_ > faster. Threadlets behave much worse without event driven model, events can behave worse without backed threads, they are mutually compensating. I posted kevent/epoll benchmarks and related design issues too many times both with handmade applications (which might be broken as hell) and popular open-source servers to repeat them again. > Pavel > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- Evgeniy Polyakov