From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gautam Thaker Subject: 2.6.26.6-rt11 nanosleep() does have accurate behavior Date: Fri, 07 Nov 2008 10:56:02 -0500 Message-ID: <49146512.4020107@atl.lmco.com> Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=ISO-8859-1 Content-Transfer-Encoding: 7BIT Cc: "Gautam H. Thaker - LM ATL" To: linux-rt-users@vger.kernel.org Return-path: Received: from mailgw1a.lmco.com ([192.31.106.7]:44189 "EHLO mailgw1a.lmco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752014AbYKGQDD (ORCPT ); Fri, 7 Nov 2008 11:03:03 -0500 Received: from emss07g01.ems.lmco.com (relay5.ems.lmco.com [166.29.2.16])by mailgw1a.lmco.com (LM-6) with ESMTP id mA7Fu79Z017585for ; Fri, 7 Nov 2008 08:56:07 -0700 (MST) Received: from CONVERSION2-DAEMON.lmco.com by lmco.com (PMDF V6.3-x14 #31428) id <0K9Z0050109JWX@lmco.com> for linux-rt-users@vger.kernel.org; Fri, 07 Nov 2008 08:56:07 -0700 (MST) Received: from enterprise.atl.lmco.com ([166.17.240.20]) by lmco.com (PMDF V6.3-x14 #31428) with ESMTP id <0K9Z00GEH09EFE@lmco.com> for linux-rt-users@vger.kernel.org; Fri, 07 Nov 2008 08:56:02 -0700 (MST) Sender: linux-rt-users-owner@vger.kernel.org List-ID: I recently started to study how nanosleep() behaves under 2.6.26.6-rt11 compiled in in FULL PREEMPT, uniprocessor mode. I find that between 2.6.20-rt8 and this new kernel something has changed and nanosleep() is back to its old behavior or sleeping for next higher number of msec rather than carefully following the "y=x" line. I don't follow the RT world closely enough, but is this a regression or an expected change in behavior? The link below show the results very clearly. http://www.atl.external.lmco.com/projects/QoS/documents/nanosleep_1.png Gautam