Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754668AbaBMNDI (ORCPT ); Thu, 13 Feb 2014 08:03:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:3317 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754632AbaBMNDG (ORCPT ); Thu, 13 Feb 2014 08:03:06 -0500 Date: Thu, 13 Feb 2014 14:02:28 +0100 From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , Stephane Eranian , Don Zickus , LKML , Joe Mario , Richard Fowles Subject: Re: [PATCH 00/21] perf, c2c: Add new tool to analyze cacheline contention on NUMA systems Message-ID: <20140213130228.GB2908@krava.brq.redhat.com> References: <20140211071401.GG27965@twins.programming.kicks-ass.net> <20140211105217.GS9987@twins.programming.kicks-ass.net> <20140211110242.GU9987@twins.programming.kicks-ass.net> <20140211111421.GN27965@twins.programming.kicks-ass.net> <20140211115013.GE28757@ghostprotocols.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140211115013.GE28757@ghostprotocols.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 On Tue, Feb 11, 2014 at 08:50:13AM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Feb 11, 2014 at 12:14:21PM +0100, Peter Zijlstra escreveu: > > On Tue, Feb 11, 2014 at 12:08:56PM +0100, Stephane Eranian wrote: > > > Assuming you can decode and get the info about the base registers used, > > > you'd have to do this for each arch with load/store sampling capabilities. > > > this is painful compared to getting the portable info from dwarf directly. > > > But its useful now, as compared to whenever GCC gets around to > > implementing more dwarves and that GCC getting used widely enough to > > actually rely on it. > > > All you need for the decode is a disassembler, and every arch should > > already have multiple of those. Should be easy to reuse one, right? > > Yeah, I never got around to actually try to implement this, but my > feeling was that all the bits and pieces were there already: > > 1) the precise IP for the instruction, that disassembled would tell > which registers were being operated on, or memory that we would "reverse > map" to a register > > 2) DWARF expression locations that allows us to go from registers to a > variable/parameter and thus to a type > > 3) PERF_SAMPLE_REGS_USER (from a quick look, why do we have "USER" in > it? Jiri?) well, it was meant for store user registers only to assists user DWARF unwind we can add PERF_SAMPLE_REGS_KERNEL > > 4) libunwind have register maps for various arches, so probably > something there could be reused here as well (Jiri?) not sure what you mean by 'something' here.. but yep, libunwind does have register maps for various arches jirka -- 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/