From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933730AbXHHKVQ (ORCPT ); Wed, 8 Aug 2007 06:21:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751088AbXHHKU6 (ORCPT ); Wed, 8 Aug 2007 06:20:58 -0400 Received: from one.firstfloor.org ([213.235.205.2]:41031 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbXHHKU5 (ORCPT ); Wed, 8 Aug 2007 06:20:57 -0400 Date: Wed, 8 Aug 2007 12:20:56 +0200 From: Andi Kleen To: Sheplyakov Alexei Cc: Andi Kleen , dragoran , linux-kernel@vger.kernel.org Subject: Re: allow non root users to set io priority "idle" ? Message-ID: <20070808102056.GC12861@one.firstfloor.org> References: <46B6EDCB.6030806@gmail.com> <20070808095132.GA31020@theor.jinr.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070808095132.GA31020@theor.jinr.ru> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 08, 2007 at 01:51:32PM +0400, Sheplyakov Alexei wrote: > On Mon, Aug 06, 2007 at 01:11:01PM +0200, Andi Kleen wrote: > > > Very low priority can starve others when it holds some kernel resource > > needed by another task. > > Nevertheless ordinary users are permitted to lower priority ([re]nice) Low priority as allowed by renice is ok -- the resource holder will run eventually and the system make progress. > I don't quite understand. There are a lot of other ways to starve such > high-priority process: > 1. renice the low-priority process That requires user action. e.g. if you google a bit you can find a famous story where the NASA had to do that remotely to solve a PI problem on one of the Mars rovers. But I'm sure they weren't very pleased about it. And not everybody has a JPL control room to patch things up in the backhand. > 2. send it a signal > 3. ptrace it Only root can do these. -Andi