From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933169AbcFGVCm (ORCPT ); Tue, 7 Jun 2016 17:02:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1719 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932941AbcFGVCk (ORCPT ); Tue, 7 Jun 2016 17:02:40 -0400 Date: Tue, 7 Jun 2016 16:02:37 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Mel Gorman , Matt Fleming , Srikar Dronamraju Subject: Re: [PATCH 2/2] sched/debug: fix deadlock when enabling sched events Message-ID: <20160607210237.kdkqm7typivv75l7@treble> References: <50a0f7f2a5f8d69e0440c3430f06be7ccbe59903.1465322027.git.jpoimboe@redhat.com> <20160607195448.GL30154@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160607195448.GL30154@twins.programming.kicks-ass.net> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 07 Jun 2016 21:02:39 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 07, 2016 at 09:54:48PM +0200, Peter Zijlstra wrote: > On Tue, Jun 07, 2016 at 02:43:17PM -0500, Josh Poimboeuf wrote: > > 1. Instead of just warning and allowing the tracepoints to be broken, > > I'd argue that it would be better to make them work by forcing > > schedstats enabled and printing a warning about that, which is what's > > Forcing them enabled doesn't make them useful per se; some of these > tracepoint rely on previously recoded state, which now wasn't previously > recorded because back then it was disabled. Ah, that's true. Though this issue exists regardless of whether we force enable schedstats or the user manually enables them. It's a side effect of allowing schedstats to be enabled after booting. -- Josh