From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755329AbZBIUKi (ORCPT ); Mon, 9 Feb 2009 15:10:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752972AbZBIUK2 (ORCPT ); Mon, 9 Feb 2009 15:10:28 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:51592 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752107AbZBIUK1 (ORCPT ); Mon, 9 Feb 2009 15:10:27 -0500 X-AuthUser: davidel@xmailserver.org Date: Mon, 9 Feb 2009 12:10:23 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: mtk.manpages@gmail.com cc: Linux Kernel Mailing List , Thomas Gleixner , Andrew Morton Subject: Re: [patch 2/2] timerfd extend clockid support In-Reply-To: Message-ID: References: User-Agent: Alpine 1.10 (DEB 962 2008-03-14) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Feb 2009, Michael Kerrisk wrote: > > and I did not have even the time to peek > > into the core timer code to see if the usage of other timer types in > > eventfd would create problems. That's why I asked Thomas if they'd behave > > differently from an hrtimer caller POV. > > I'll try to take a look by myself today or tomorrow. > > Okay -- hopefully my test program may be useful (even if it is not > itself fully tested yet, it's patterned after a similar test program I > wrote fot the POSIX timers API, so it should mostly work). Answer was pretty easy once you look at the code :) Timerfd uses core hrtimer functions, and clockids different from the ones timerfd already handles, fall into the CPU-timers domain. Domain that is not handled by hrtimer. Changes to timerfd to support CPU-based timers are really deep (more than changes, is a total rewrite). not only to timerfd, but also to CPU-based timers to deliver notification by means different than signals. Given the amount of code change, and given that a posix-timers->signalfd bridge could solve the problem, I'm not going even close to suggest such a change. - Davide