Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756349Ab1DVRBj (ORCPT ); Fri, 22 Apr 2011 13:01:39 -0400 Received: from mga01.intel.com ([192.55.52.88]:21286 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756110Ab1DVRBi (ORCPT ); Fri, 22 Apr 2011 13:01:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.64,254,1301900400"; d="scan'208";a="682590309" Date: Fri, 22 Apr 2011 10:00:55 -0700 From: Andi Kleen To: arun@sharma-home.net Cc: Ingo Molnar , Stephane Eranian , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Peter Zijlstra , Lin Ming , Arnaldo Carvalho de Melo , Thomas Gleixner , Peter Zijlstra , eranian@gmail.com, Arun Sharma , Linus Torvalds , Andrew Morton Subject: Re: [generalized cache events] Re: [PATCH 1/1] perf tools: Add missing user space support for config1/config2 Message-ID: <20110422170055.GB16607@tassilo.jf.intel.com> References: <20110422092322.GA1948@elte.hu> <20110422105211.GB1948@elte.hu> <20110422165007.GA18401@vps.sharma-home.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110422165007.GA18401@vps.sharma-home.net> 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 Content-Length: 945 Lines: 24 > One could argue that all you need is cycles and instructions. If there is an > expensive load, you'll see that the load instruction takes many cycles and > you can infer that it's a cache miss. That is when you can actually recognize which of the last load instructions caused the problem. Often skid on Out of order CPUs makes this very hard to identify which actual load caused the the long stall (or if they all stalled) There's a way around it of course using advanced events, but not with cycles. > I don't see why exposing all vendor defined events is harmful Simple: without vendor events you cannot answer a lot of questions. -Andi -- ak@linux.intel.com -- Speaking for myself only -- 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/