From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933582AbXLMVhx (ORCPT ); Thu, 13 Dec 2007 16:37:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759381AbXLMVhg (ORCPT ); Thu, 13 Dec 2007 16:37:36 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:56507 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933539AbXLMVhf (ORCPT ); Thu, 13 Dec 2007 16:37:35 -0500 Date: Thu, 13 Dec 2007 22:37:11 +0100 From: Ingo Molnar To: "Eric W. Biederman" Cc: Thomas Gleixner , Linux Containers , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Mark timer_stats as incompatible with multiple pid namespaces Message-ID: <20071213213710.GB25563@elte.hu> References: <20071213090102.GB1926@elte.hu> <20071213130423.GB28340@elte.hu> <20071213202621.GC25130@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Eric W. Biederman wrote: > >> Well struct pid * works in that case if you grab the reference to > >> it. > > > > but the display of the stats might happen much later. The point of > > this API is to save pid+comm, which gives users a good idea about > > what caused the events in the past - without having to pin any > > resource of that task. > > Likewise struct pid is designed not to be a problem if pinned. It is a > little heavier then it used to be with the addition of pid namespace > support but not much. And if it is to heavy struct pid needs to be > fixed. > > Holding the struct pid very much does not pin the task struct, and it > shouldn't pin any other resources. I agree 64bytes or so is a bit > more to pin then 4 bytes but it really isn't a lot. yeah, and i have no conceptual objections - i just wanted to outline the thinking behind /proc/timer_stats. Ingo