From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754792Ab0CEHUs (ORCPT ); Fri, 5 Mar 2010 02:20:48 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:52956 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753868Ab0CEHUr (ORCPT ); Fri, 5 Mar 2010 02:20:47 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: figo zhang Subject: Re: sched_fair: vruntime and min_vruntime will be overflow? Cc: kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org In-Reply-To: References: Message-Id: <20100305161458.3A8D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Fri, 5 Mar 2010 16:20:43 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > hi, > > when enqueue or dequeue the task, the se->vruntime and cfs_rq->min_vruntime will > increased, i want to know it is will be overflow in future time? Let's quick calculation. type of vruntime is u64. 1 year = 365 x 24 x 60 x 60 x 1000 x 1000 x 1000 nanosec ~= 3 x 10^16 ~= 2^55 2^64 / 2^55 = 2^9 ~= 500 year. then, 500 years after you can see overflow if you still live. :)