Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756944AbYLEMXT (ORCPT ); Fri, 5 Dec 2008 07:23:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751984AbYLEMXL (ORCPT ); Fri, 5 Dec 2008 07:23:11 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:58208 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751980AbYLEMXK (ORCPT ); Fri, 5 Dec 2008 07:23:10 -0500 Date: Fri, 5 Dec 2008 07:23:07 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: "Eric W. Biederman" cc: Ingo Molnar , Andrew Morton , linux-kernel@vger.kernel.org, Frederic Weisbecker , Peter Zijlstra , Dave Hansen , containers@lists.osdl.org, Sukadev Bhattiprolu , "Serge E. Hallyn" , Steven Rostedt Subject: Re: [PATCH 3/3] ftrace: add ability to only trace swapper tasks In-Reply-To: Message-ID: References: <20081204052638.425740534@goodmis.org> <20081204052735.362609481@goodmis.org> <20081204001803.598063f5.akpm@linux-foundation.org> <20081204091023.GJ32594@elte.hu> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1722 Lines: 52 On Thu, 4 Dec 2008, Eric W. Biederman wrote: > Steven Rostedt writes: > > > On Thu, 4 Dec 2008, Eric W. Biederman wrote: > >> > >> Right. I simply meant most of the > >> if (likely(p->pid)) conditional except for the counts is pretty much a don't > >> care. Keeping the idle tasks off of the process list and out of the counts > >> is useful. > >> > >> For this particular case what problem did you see with calling attach_pid > >> with PIDTYPE_PID on init_struct_pid? > > > > On boot up, the CPU 0 idle task is attached to init_struct_pid, and not > > the others. If you do a "attach_pid" on the next idle task that is created, > > it will become the attched process, bumping off CPU 0's idle task from the > > init_struct_pid. > > It should form a linked list. For other pid types we don't have a problem. Other pids get allocated per task. In the beginning of copy_process we have: if (pid != &init_struct_pid) { retval = -ENOMEM; pid = alloc_pid(task_active_pid_ns(p)); Where alloc_pid allocates a pid structure. But this is only done if it is not a swapper task. > > > When doing the code you suggested, I end up with only marking the last > > idle task to be created. > > Odd. It is all a linked list through the task structures. > I'm guessing the initialization isn't quite right. > > Weird. Do I need to change the loop to do_each_pid_thread? I'll try that later today. -- Steve -- 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/