Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757555AbYFWJsS (ORCPT ); Mon, 23 Jun 2008 05:48:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753571AbYFWJsE (ORCPT ); Mon, 23 Jun 2008 05:48:04 -0400 Received: from py-out-1112.google.com ([64.233.166.178]:12829 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753399AbYFWJsC (ORCPT ); Mon, 23 Jun 2008 05:48:02 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=gRjVd5uHW/6o9gVzX8qg/yIJFhxnQdUQWGVBDWm+kte/ny59805WDY58+Fy4ljhPGu L0MJe9k48zJrv1OXUfY72n87xCtdNRwsb0w4X42hS9CVYV2Lm9q7mpD5Fy0ygkovrI8F OvaL0zu4ynebuHymlnV9wne2kZkl7Y9AIZxiA= Message-ID: Date: Mon, 23 Jun 2008 11:48:00 +0200 From: "Michael Kerrisk" To: "Bart Van Assche" Subject: Re: nanosleep() uses CLOCK_MONOTONIC, should be CLOCK_REALTIME? Cc: "Michael Kerrisk" , lkml , "Thomas Gleixner" , "john stultz" , "Ingo Molnar" , "Roman Zippel" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <485E00CD.9060503@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1783 Lines: 49 Bart, On Mon, Jun 23, 2008 at 10:34 AM, Bart Van Assche wrote: > On Sun, Jun 22, 2008 at 9:35 AM, Michael Kerrisk wrote: >> Thomas, >> >> (I gues you are the right target for this?) >> >> The POSIX.1 specification of nanosleep() says: >> >> But, except for the case of being interrupted by a signal, the >> suspension time shall not be less than the time specified by >> rqtp, as measured by the system clock CLOCK_REALTIME. >> >> >> However, reading kernel/hrtimer.c:sys_nanosleep(), it appears that >> CLOCK_MONOTONIC is used. >> >> return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC); >> >> Is there a reason to use CLOCK_MONOTONIC, instead of CLOCK_REALTIME? Is it >> intentional? If yes, then I should document this in the man-pages. If not, >> then it should be fixed. > > CLOCK_MONOTONIC works fine even if ntpd steps the clock forward or > backward, CLOCK_REALTIME not. So the man page should be fixed. Thanks for your reply, but I'm not quite convinced yet. The things is: the Solaris man page also says "CLOCK_REALTIME". (Of course that man page may just be parroting the standard.) Could there not be some reasonable semantics for a nanosleep() that was based on CLOCK_REALTIME? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.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/