From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: perf: prctl(PR_TASK_PERF_EVENTS_DISABLE) has no effect Date: Fri, 27 Jan 2012 22:34:23 +0100 Message-ID: <1327700063.2446.178.camel@twins> References: <4F22D8D9.3010108@rgmadvisors.com> <1327684363.2446.176.camel@twins> <4F2303D8.80300@rgmadvisors.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from merlin.infradead.org ([205.233.59.134]:56049 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751530Ab2A0Ved convert rfc822-to-8bit (ORCPT ); Fri, 27 Jan 2012 16:34:33 -0500 In-Reply-To: <4F2303D8.80300@rgmadvisors.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Andrew Steets Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo On Fri, 2012-01-27 at 14:06 -0600, Andrew Steets wrote: > On 1/27/12 11:12 AM, Peter Zijlstra wrote: > > On Fri, 2012-01-27 at 11:03 -0600, Andrew Steets wrote: > >> Can anyone tell > >> me if I'm using this wrong or if this is a bug? > > > > You're using it wrong, it will disable events you own (created) not > > events that monitor you. > > Is there an alternate way of disabling events that monitor the current > process? Nope, nor will there ever be. > I ask because I came across the following description in > tools/perf/design.txt: > > A process can enable or disable all the counter groups that are > attached to it, using prctl: > > prctl(PR_TASK_PERF_EVENTS_ENABLE); > > prctl(PR_TASK_PERF_EVENTS_DISABLE); > > This applies to all counters on the current process, whether created > by this process or by another, and doesn't affect any counters that > this process has created on other processes. It only enables or > disables the group leaders, not any other members in the groups. That's wrong.. also I wouldn't ever allow such a 'feature', that's just asking for trouble.