From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12698C48BD6 for ; Wed, 26 Jun 2019 16:04:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD74B2182B for ; Wed, 26 Jun 2019 16:04:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726531AbfFZQEP (ORCPT ); Wed, 26 Jun 2019 12:04:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:45340 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbfFZQEP (ORCPT ); Wed, 26 Jun 2019 12:04:15 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 09AAE217D7; Wed, 26 Jun 2019 16:04:13 +0000 (UTC) Date: Wed, 26 Jun 2019 12:04:12 -0400 From: Steven Rostedt To: Thomas Preisner Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH] ftrace: add simple oneshot function tracer Message-ID: <20190626120412.662e8cf9@gandalf.local.home> In-Reply-To: <20190623120555.nka2357agpqovxla@stud.informatik.uni-erlangen.de> References: <20190529104552.146fa97c@oasis.local.home> <20190612212935.4xq6dyua5d5vrrvj@stud.informatik.uni-erlangen.de> <20190617201627.647547c7@gandalf.local.home> <20190623120555.nka2357agpqovxla@stud.informatik.uni-erlangen.de> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 23 Jun 2019 14:05:55 +0200 Thomas Preisner wrote: > I've created this tracer with kernel tailoring in mind since the > tailoring process of e.g. undertaker heavily benefits from a more > precise set of input data. > > A "oneshot" option for the function tracer would be a viable > possibility. However, this may add a lot of overhead (performance wise) > in comparison to my current approach? After all, the use case of my > tracer would be some sort of kernel activity monitoring during "normal > usage" in order to get a grasp of (hopefully) all required kernel > functions. Coming back from vacation and not having this threaded in my inbox, I have to ask (to help cache this back into my head), what was the "current approach" compared to the "oneshot" option, and why would it have better performance? > > Also, there is no strong reason to add a new event type, > this was just a means of reducing the collected data (which may as well > be omitted since there is no real benefit). +1 > > My "oneshot tracer" actually collects and outputs every parent in order > to get a more thorough view on used kernel code. Therefore, I would > suggest to keep this functionality and maybe make it configurable > instead? Configure which? (again, coming back from vacation, I need a refresher on this ;-) -- Steve