From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chris Friesen" Subject: looking for explanation of select() timeout behaviour Date: Mon, 23 Jun 2008 10:00:26 -0600 Message-ID: <485FC89A.30309@nortel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Linux Kernel To: netdev@vger.kernel.org Return-path: Received: from zcars04e.nortel.com ([47.129.242.56]:38518 "EHLO zcars04e.nortel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754049AbYFWQAe (ORCPT ); Mon, 23 Jun 2008 12:00:34 -0400 Sender: netdev-owner@vger.kernel.org List-ID: I've got something odd in a recent strace log (running on an older kernel, I haven't yet tried to reproduce in mainline): 20418 22:06:50.583303 select(19, [7 11 12 13 14 15 16 17 18], NULL, NULL, {0, 498508}) = 1 (in [11], left {0, 0}) <5.074137> select() was called with a timeout of half a second. Five seconds later it returns with zero time left and a single socket readable. Why wouldn't it have returned after half a second with a timeout? My immediate suspicion would be to look at scheduler behaviour, but are there any other explanations? I'm fairly sure system time wasn't changed during this interval (the system should have been ntp-synced). Thanks, Chris