Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934034AbbDWWub (ORCPT ); Thu, 23 Apr 2015 18:50:31 -0400 Received: from mail-ig0-f176.google.com ([209.85.213.176]:32947 "EHLO mail-ig0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932841AbbDWWua (ORCPT ); Thu, 23 Apr 2015 18:50:30 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150423190825.714359844@goodmis.org> <20150423160925.7d108eaa@gandalf.local.home> Date: Thu, 23 Apr 2015 15:50:29 -0700 X-Google-Sender-Auth: XQ77QYUBfHoIerLZvu2Dlsymb-I Message-ID: Subject: Re: [RFC][PATCH 0/4] tracing: Add new hwlat_detector tracer From: Linus Torvalds To: Thomas Gleixner Cc: Steven Rostedt , Linux Kernel Mailing List , "linux-rt-users@vger.kernel.org" , Ingo Molnar , Andrew Morton , Peter Zijlstra , Carsten Emde , Daniel Wagner , Jon Masters , Clark Williams Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 976 Lines: 20 On Thu, Apr 23, 2015 at 1:21 PM, Thomas Gleixner wrote: > > But at least on the machines which have the event counter it would be > usefull to include that information as well. In fact, I'd argue that we should *not* do this odd magic latency measurement thing at all, exactly because Intel gave is the SMI counter, and it's much more likely to be useful in real life. The odd "stop machine and busy loop adn do magic" thing is a incredibly invasive hack that sane people will never enable at all, while the "add support for the hadrware we asked for and got" is a small thing that we can do on all modern Intel chips, and can be enabled by default because there is no downside. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/