Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760886AbXHHLzp (ORCPT ); Wed, 8 Aug 2007 07:55:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751837AbXHHLzh (ORCPT ); Wed, 8 Aug 2007 07:55:37 -0400 Received: from one.firstfloor.org ([213.235.205.2]:42354 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751521AbXHHLzg (ORCPT ); Wed, 8 Aug 2007 07:55:36 -0400 Date: Wed, 8 Aug 2007 13:55:35 +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: <20070808115535.GB13878@one.firstfloor.org> References: <46B6EDCB.6030806@gmail.com> <20070808095132.GA31020@theor.jinr.ru> <20070808102056.GC12861@one.firstfloor.org> <20070808114949.GA8465@theor.jinr.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070808114949.GA8465@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 Content-Length: 851 Lines: 19 > The original question (unless I'm missing something) was "why _the owner_ > of a process is not enabled to lower its IO priority?" The owner of the > process certainly can send signal and ptrace it. Ah I misparsed you. Sending signals and ptraces is atomic regarding system operations. This means the kernel will finish doing whatever it is doing (or bail out releasing all resources) before processing them. So stopping a process this way can never starve its IO. Ok there are special cases like user space FUSE or NFS servers that can block operations, but these are expected to run as root. -Andi - 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/