From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757857AbYDCXsW (ORCPT ); Thu, 3 Apr 2008 19:48:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753530AbYDCXsQ (ORCPT ); Thu, 3 Apr 2008 19:48:16 -0400 Received: from gateway-1237.mvista.com ([63.81.120.158]:57557 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbYDCXsQ (ORCPT ); Thu, 3 Apr 2008 19:48:16 -0400 Message-ID: <47F56CBC.4080706@ct.jp.nec.com> Date: Thu, 03 Apr 2008 16:48:12 -0700 From: Hiroshi Shimamoto User-Agent: Thunderbird 2.0.0.12 (Windows/20080213) MIME-Version: 1.0 To: Andrew Morton Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, a.p.zijlstra@chello.nl Subject: Re: [RESEND][RFC v3 PATCH] RTTIME watchdog timer proc interface References: <47F55D8D.3060700@ct.jp.nec.com> <20080403161106.fe260fd7.akpm@linux-foundation.org> In-Reply-To: <20080403161106.fe260fd7.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Thu, 03 Apr 2008 15:43:25 -0700 > Hiroshi Shimamoto wrote: > >> From: Hiroshi Shimamoto >> >> Introduce new proc interface for RTTIME watchdog. >> It makes administrator able to set RTTIME watchdog to exisiting real-time >> applications without impact. It's useful we don't want to change software >> stack, but want to use RTTIME watchdog for that software. > > Well you don't really need to change the software stack. It's a matter of > setting RLIMIT_RTTIME in the parent process before starting the stack up. I think it means all processes have the same RTTIME, I cannot change some of them, correct? > This is not much more work than poking at /proc//rttime afterwards. > > Although setting RLIMIT_RTTIME via fork() is much less useful than being > able to alter it at runtime. > >> fs/proc/base.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > And that's rather a lot of new code just for RLIMIT_RTTIME. And > RLIMIT_RTTIME is not the only rlimit which has this problem - generally the > rlimit interface is a rather nasty one. > > > I think we should look at creating a general way of modifying and reading a > running process's rlimits. If we want to do that, a syscall would be the > appropriate interface. > I agreed, using /proc is easy but wrong way. I'll look for other approach for this. thanks, Hiroshi Shimamoto