Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758521AbaDVVYb (ORCPT ); Tue, 22 Apr 2014 17:24:31 -0400 Received: from mail-oa0-f49.google.com ([209.85.219.49]:45347 "EHLO mail-oa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbaDVVYZ (ORCPT ); Tue, 22 Apr 2014 17:24:25 -0400 MIME-Version: 1.0 In-Reply-To: <20140422205439.GM22728@two.firstfloor.org> References: <20140422180305.GK8488@redhat.com> <20140422205439.GM22728@two.firstfloor.org> Date: Tue, 22 Apr 2014 23:24:24 +0200 Message-ID: Subject: Re: mapping instructions to dynamic languages like java, python, ruby From: Stephane Eranian To: Andi Kleen Cc: Don Zickus , Peter Zijlstra , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , LKML , William Cohen Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 22, 2014 at 10:54 PM, Andi Kleen wrote: >> Does anyone have any thoughts or experience on this? > > perf has a JIT interface today, but it's extremely primitive > and only supports symbols. Clearly it could be done better. > > Various JITs (e.g. Java) have special debug interfaces for this. > > Various non perf profilers support it too. e.g. Vtune has a special > API for it: > https://software.intel.com/sites/default/files/jit_profiling_api_lin_0.pdf > > Essentially you would need to write a JIT specific adapter > that translates to perf format. Or emulate the Vtune interface > and reuse existing Vtune adaptations. > > perf record needs some kind of side band interface where the JIT adapter > can report to it: > - symbols > - the assembler code (so it can be shown) > - source lines > - report any changes when JITed code changes > Forgot to mention that my implementation does go all the way to jitted code assembly view via perf annotate + source view. So it does cover all aspects. As for attaching to a running JIT, this again needs some cooperation from JIT environment. > Then perf record could put that information into the perf.data. > > In theory that information could be passed through the kernel, > but just using some user protocol (unix sockets or files) would be > likely enough. The current interface uses files in /tmp. > I would likely change that, it's not clear even if it's secure. > > It's likely a substantial project. > > It would be even useful for the kernel, as the kernel does JITing > itself these days. > > -Andi -- 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/