From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: m4/clock_time.m4 from r117596 Date: Thu, 31 Jul 2014 22:54:19 -0700 Organization: UCLA Computer Science Department Message-ID: <53DB2B8B.1060706@cs.ucla.edu> References: <53D5EE3D.3090401@yandex.ru> <53DAA4B9.9000509@cs.ucla.edu> <53DB28EA.8050301@yandex.ru> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1406872485 13254 80.91.229.3 (1 Aug 2014 05:54:45 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 1 Aug 2014 05:54:45 +0000 (UTC) Cc: Emacs development discussions To: Dmitry Antipov Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Aug 01 07:54:40 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XD5nb-00084O-3d for ged-emacs-devel@m.gmane.org; Fri, 01 Aug 2014 07:54:39 +0200 Original-Received: from localhost ([::1]:60049 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XD5na-0002SG-QK for ged-emacs-devel@m.gmane.org; Fri, 01 Aug 2014 01:54:38 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:50231) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XD5nT-0002SA-97 for emacs-devel@gnu.org; Fri, 01 Aug 2014 01:54:36 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XD5nN-0007qV-Nn for emacs-devel@gnu.org; Fri, 01 Aug 2014 01:54:31 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:53011) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XD5nN-0007qN-Ha for emacs-devel@gnu.org; Fri, 01 Aug 2014 01:54:25 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id 1CFF7A6007A; Thu, 31 Jul 2014 22:54:24 -0700 (PDT) X-Virus-Scanned: amavisd-new at smtp.cs.ucla.edu Original-Received: from smtp.cs.ucla.edu ([127.0.0.1]) by localhost (smtp.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7KO5BN9C1xsI; Thu, 31 Jul 2014 22:54:19 -0700 (PDT) Original-Received: from [192.168.1.9] (pool-108-0-233-62.lsanca.fios.verizon.net [108.0.233.62]) by smtp.cs.ucla.edu (Postfix) with ESMTPSA id 9196AA60078; Thu, 31 Jul 2014 22:54:19 -0700 (PDT) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 In-Reply-To: <53DB28EA.8050301@yandex.ru> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 131.179.128.62 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:173342 Archived-At: Dmitry Antipov wrote: > Are you sure about that? On my (Fedora 20) system, 'man timer_settime' and > 'man timerfd_settime' says nothing about resolution and rounding. It's a POSIX requirement for timer_settime, and I expect timerfd_settime to be similar. I'd be surprised if the Linux kernel did it any differently. A bit of reflection should make it clear why this is so (and why clock_settime is different): an application must always allow for the act of computation to advance the clock a little bit, so if the system rounds timers up and clocks down it won't hurt apps any more than they're hurt already simply by running. Here's the POSIX requirement: "Time values that are between two consecutive non-negative integer multiples of the resolution of the specified timer shall be rounded up to the larger multiple of the resolution." http://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_settime.html