From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932307AbcCHKL5 (ORCPT <rfc822;w@1wt.eu>);
	Tue, 8 Mar 2016 05:11:57 -0500
Received: from casper.infradead.org ([85.118.1.10]:56157 "EHLO
	casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753551AbcCHKLn (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 8 Mar 2016 05:11:43 -0500
Date: Tue, 8 Mar 2016 11:11:34 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: lizefan@huawei.com, hannes@cmpxchg.org, mingo@redhat.com, acme@kernel.org,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        kernel-team@fb.com
Subject: Re: [PATCH 2/2] cgroup, perf_event: make perf_event controller work
 on cgroup2 hierarchy
Message-ID: <20160308101133.GW6344@twins.programming.kicks-ass.net>
References: <1456351975-1899-1-git-send-email-tj@kernel.org>
 <1456351975-1899-3-git-send-email-tj@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1456351975-1899-3-git-send-email-tj@kernel.org>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Feb 24, 2016 at 05:12:55PM -0500, Tejun Heo wrote:
> perf_event is a utility controller whose primary role is identifying
> cgroup membership to filter perf events; however, because it also
> tracks some per-css state, it can't be replaced by pure cgroup
> membership test.  Mark the controller as implicitly enabled on the
> default hierarchy so that perf events can always be filtered based on
> cgroup v2 path as long as the controller is not mounted on a legacy
> hierarchy.
> 
> "perf record" is updated accordingly so that it searches for both v1
> and v2 hierarchies.  A v1 hierarchy is used if perf_event is mounted
> on it; otherwise, it uses the v2 hierarchy.
> 
> v2: Doc updated to reflect more flexible rebinding behavior.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>

Arnaldo, do the userspace bits look ok?