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 12:41:08 -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 09:46:28 -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: > >> Ingo Molnar writes: >> >> > * Andrew Morton wrote: >> > >> >> > Signed-off-by: Steven Rostedt >> >> >> >> What does this patch actually do? Is swapper currently excluded from >> >> tracing for undisclosed reasons and this patch permits it to be traced? >> >> If so, why was swapper thus excluded? Or am I totally off track? >> > >> >> > +static struct pid * const ftrace_swapper_pid = (struct pid *)1; >> >> >> >> eh? >> > >> > all side-effects of getting rid of the integer based PID namespace and >> > replacing them with struct pid pointers. >> >> Thanks for asking Andrew it looks like an unnecessary side effect. > > Well, it was necessary without hacking fork.c ;-) The (struct pid *)1 has always been unnecessary. As for fork. It would be nice to remove most of the special cases for the idle thread. At least the counts are significant. The rest is pretty much a don't care at this point. Eric