From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH 3/3] ftrace: add ability to only trace swapper tasks Date: Thu, 04 Dec 2008 23:43:52 -0800 Message-ID: References: <20081204052638.425740534@goodmis.org> <20081204052735.362609481@goodmis.org> <20081204001803.598063f5.akpm@linux-foundation.org> <20081204091023.GJ32594@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: (Steven Rostedt's message of "Thu, 4 Dec 2008 16:56:28 -0500 (EST)") Sender: linux-kernel-owner@vger.kernel.org To: Steven Rostedt 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 List-Id: containers.vger.kernel.org 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. > 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. Eric