Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757152AbXIVRF3 (ORCPT ); Sat, 22 Sep 2007 13:05:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753684AbXIVRFV (ORCPT ); Sat, 22 Sep 2007 13:05:21 -0400 Received: from www.osadl.org ([213.239.205.134]:52615 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752359AbXIVRFU (ORCPT ); Sat, 22 Sep 2007 13:05:20 -0400 Subject: Re: RFC: A revised timerfd API From: Thomas Gleixner To: Michael Kerrisk Cc: Bernd Eckenfels , linux-kernel@vger.kernel.org, Ulrich Drepper , geoff@gclare.org.uk, Andrew Morton , Christoph Hellwig , Jonathan Corbet , Randy Dunlap , vda.linux@googlemail.com, Linus Torvalds , Lee Schermerhorn , David =?ISO-8859-1?Q?H=E4rdeman?= , mtk-manpages@gmx.net In-Reply-To: <517f3f820709220907l4c4e693di3df6942bdca5bcfa@mail.gmail.com> References: <46F514C9.5010208@gmx.net> <517f3f820709220907l4c4e693di3df6942bdca5bcfa@mail.gmail.com> Content-Type: text/plain Date: Sat, 22 Sep 2007 19:05:17 +0200 Message-Id: <1190480717.4035.45.camel@chaos> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 (2.12.0-3.fc8) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1464 Lines: 44 On Sat, 2007-09-22 at 18:07 +0200, Michael Kerrisk wrote: > Hello Bernd, > > Please don't trim the CC list when replying! I nearly did not see > your reply, and others will have missed it also. Yup. > On 9/22/07, Bernd Eckenfels wrote: > > In article <46F514C9.5010208@gmx.net> you wrote: > > > 1. This design stretches the POSIX timers API in strange > > > ways. > > > > Maybe it is possible to reimplement the POSIX API in usermode using the > > kernel's FD implementation? Yikes. > It's a clever idea... Without thinking on it too long, I'm not sure > whether or not there might be some details which would make this > difficult. You'd need be quite masochistic to start such a project. The POSIX timer API consists mostly of corner cases and I doubt that you get them even halfway under control in a pure user space implementation. It would be a rather huge performance penalty as well. You need at least two user space context switches to get the most simple cases resolved. > > (and drop the posix support from kernel) > > However we couldn't drop POSIX support from the kernel, because that > would break the ABI. True. So there is no point in reinventing the wheel. tglx - 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/