From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753900AbcKINOc (ORCPT ); Wed, 9 Nov 2016 08:14:32 -0500 Received: from mail.kernel.org ([198.145.29.136]:48338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752163AbcKINOa (ORCPT ); Wed, 9 Nov 2016 08:14:30 -0500 Date: Wed, 9 Nov 2016 10:14:26 -0300 From: Arnaldo Carvalho de Melo To: Andi Kleen Cc: linux-kernel@vger.kernel.org, Andi Kleen , adrian.hunter@intel.com Subject: Re: [PATCH] perf tools pt: Remove obsolete paragraph in intel-pt.c Message-ID: <20161109131426.GD12125@kernel.org> References: <1478650260-30140-1-git-send-email-andi@firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1478650260-30140-1-git-send-email-andi@firstfloor.org> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Nov 08, 2016 at 04:11:00PM -0800, Andi Kleen escreveu: > From: Andi Kleen > > Since the unprivileged sched switch event was added in perf, > PT doesn't need need perf_event_paranoid=-1 anymore for > per cpu decoding. So remove the obsolete paragraph in > the documentation. Thanks for pointing that out, I'll do something slightly different tho, pointing out that from kernel X.Y.Z, when the unprivileged PERF_RECORD_SWITCH metadata event was introduced, this is no longer an issue, having to be considered only on older kernels. - Arnaldo > Cc: adrian.hunter@intel.com > Signed-off-by: Andi Kleen > --- > tools/perf/Documentation/intel-pt.txt | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt > index c6c8318e38a2..c7f817fd3611 100644 > --- a/tools/perf/Documentation/intel-pt.txt > +++ b/tools/perf/Documentation/intel-pt.txt > @@ -550,16 +550,6 @@ Unless /proc/sys/kernel/perf_event_paranoid is set to -1, unprivileged users > have memory limits imposed upon them. That affects what buffer sizes they can > have as outlined above. > > -Unless /proc/sys/kernel/perf_event_paranoid is set to -1, unprivileged users are > -not permitted to use tracepoints which means there is insufficient side-band > -information to decode Intel PT in per-cpu mode, and potentially workload-only > -mode too if the workload creates new processes. > - > -Note also, that to use tracepoints, read-access to debugfs is required. So if > -debugfs is not mounted or the user does not have read-access, it will again not > -be possible to decode Intel PT in per-cpu mode. > - > - > sched_switch tracepoint > ----------------------- > > -- > 2.5.5