From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752858AbbDPVXv (ORCPT ); Thu, 16 Apr 2015 17:23:51 -0400 Received: from one.firstfloor.org ([193.170.194.197]:33548 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbbDPVXn (ORCPT ); Thu, 16 Apr 2015 17:23:43 -0400 Date: Thu, 16 Apr 2015 23:23:42 +0200 From: Andi Kleen To: Mark Rutland Cc: Kan Liang , "acme@kernel.org" , "a.p.zijlstra@chello.nl" , "eranian@google.com" , "andi@firstfloor.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH V2 1/6] perf,core: allow invalid context events to be part of sw/hw groups Message-ID: <20150416212342.GW2366@two.firstfloor.org> References: <1429084576-1078-1-git-send-email-kan.liang@intel.com> <20150416163140.GA19775@leverpostej> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150416163140.GA19775@leverpostej> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From my PoV that makes sense. One is CPU-affine, the other is not, and > the two cannot be scheduled in the same PMU transaction by the nature of > the hardware. Fundamentally, you cannot provide group semantics due to > this. Actually you can. Just use it like a free running counter, and the different groups sample it. This will work from the different CPUs, as long as the event is the same everywhere. The implemention may not be quite right yet, but the basic concept should work, and is useful. -Andi