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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 D9923C43331 for ; Mon, 11 Nov 2019 14:04:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD52C21783 for ; Mon, 11 Nov 2019 14:04:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="U3ZOYeDA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727064AbfKKOEy (ORCPT ); Mon, 11 Nov 2019 09:04:54 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:33483 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727009AbfKKOEy (ORCPT ); Mon, 11 Nov 2019 09:04:54 -0500 Received: by mail-qt1-f195.google.com with SMTP id y39so15808419qty.0 for ; Mon, 11 Nov 2019 06:04:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=XYVomfoUOz+2dXFVT1MrIwqA9RjQftapicqclx+MmeQ=; b=U3ZOYeDAezylhF8/Ittif28Vr6c8z5gRnnMr+GaYMAWii/m1ikhIodaE8tpRYm/YwN dwoNRmWz+ftp5JR2jkkowcsmb2+/zIS4X44+up2Vp/ldpbVUXR1rnWc6GXz8BXVgwRMe djGod7Fzbc5bYdWKHyLwdRag6rgkn5fe6ojMS4FsqX5+KPdj1q31y8Kl4S1PTCOdGBZQ Vf4pk8EKHd5UOnQrjgEQ6Gj5irOMQ0sFKUCnOZekLhIweNsjhLXn2RnCrh5GZwAWxXJd I6rPmdBbxZeN0/dJNlJxBIZ1Y6VOg1Xc7tEHXGpFqlBBk+iwmfCt9NBbl28TxjWxFGQi /6yQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=XYVomfoUOz+2dXFVT1MrIwqA9RjQftapicqclx+MmeQ=; b=RD70CH2s5Pv4fmgHV2RoqlLzd07Znmjw0zscxkABtP0DLE8M8ASm9of9i0wbH7txlQ Ckfy+Hmv6CBs+tlEg1hC/1lfyL+9QWv6pMuDfV3bufdUw97G1J29Zz+mH7RK6rb3aT9w qNFyE7CwjItk4ckEK9c2Mz6FKrLgL4TIuQfDAVrRqJmJ/6pprktgFV8s1l7k4FM8wQ4a W+auAqOo37psBu42EtQ0po3YATWnE+/mmxXuk72Tw+oqnm6Dsz/9KDx4bbmsFc9GVmp8 9wEvGjHECJiQH4+WtJmK2CBdT3LrBzxofdVYU3775Dr7Y/F4dYxmEq9Bp1p20lzvOwte ps4w== X-Gm-Message-State: APjAAAWm7wX2VLDihgtaXT6h/XuXlyU/4SUHNwc5N32gyrsZRD/WQvNr UNefDhfi8Jb2QQoqdjH+AWM= X-Google-Smtp-Source: APXvYqxfRziSPu4cYp648NXJXS9DdsYMnD+4dhFaNcmzTJKhl076ZDYGHCRtlJRn/ByjjECfhO6VaQ== X-Received: by 2002:aed:2799:: with SMTP id a25mr26414466qtd.226.1573481093347; Mon, 11 Nov 2019 06:04:53 -0800 (PST) Received: from quaco.ghostprotocols.net ([179.97.35.50]) by smtp.gmail.com with ESMTPSA id a18sm7971101qkc.2.2019.11.11.06.04.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Nov 2019 06:04:52 -0800 (PST) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 9C5AD411B3; Mon, 11 Nov 2019 11:04:50 -0300 (-03) Date: Mon, 11 Nov 2019 11:04:50 -0300 To: Masami Hiramatsu Cc: Ingo Molnar , Steven Rostedt , linux-kernel@vger.kernel.org, Tom Zanussi , Ravi Bangoria , Namhyung Kim Subject: Re: [PATCH v2 1/4] perf probe: Generate event name with line number Message-ID: <20191111140450.GB9365@kernel.org> References: <157314406866.4063.16995747442215702109.stgit@devnote2> <157314407850.4063.2307803945694526578.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <157314407850.4063.2307803945694526578.stgit@devnote2> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Fri, Nov 08, 2019 at 01:27:58AM +0900, Masami Hiramatsu escreveu: > Generate event name from function name with line number > as _L. Note that this is only for > the new event which is defined by the line number of > function (except for line 0). > > If there is another event on same line, you have to use > "-f" option. In that case, the new event has "_1" suffix. > > e.g. > # perf probe -a kernel_read:1 > Added new events: > probe:kernel_read_L1 (on kernel_read:1) While testing this, using the same function (kernel_read), I found it confusing that it is possible to insert probes in lines seemingly with no code, for instance: [root@quaco ~]# perf probe -a kernel_read:1 Added new event: probe:kernel_read_L1 (on kernel_read:1) You can now use it in all perf tools, such as: perf record -e probe:kernel_read_L1 -aR sleep 1 [root@quaco ~]# perf probe -a kernel_read:2 Added new event: probe:kernel_read_L2 (on kernel_read:2) You can now use it in all perf tools, such as: perf record -e probe:kernel_read_L2 -aR sleep 1 [root@quaco ~]# [root@quaco ~]# perf probe --list probe:kernel_read_L1 (on kernel_read@fs/read_write.c) probe:kernel_read_L2 (on kernel_read:1@fs/read_write.c) [root@quaco ~]# perf probe -L kernel_read 0 ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) 1 { 2 mm_segment_t old_fs; 3 ssize_t result; 5 old_fs = get_fs(); 6 set_fs(KERNEL_DS); /* The cast to a user pointer is valid due to the set_fs() */ 8 result = vfs_read(file, (void __user *)buf, count, pos); 9 set_fs(old_fs); 10 return result; } EXPORT_SYMBOL(kernel_read); [root@quaco ~]# What is the point of putting a probe on line 2? I is not initializing, etc, 1 as well, notthing there and we already have 0 (or not specifying a line number) to put a probe at the start of a function, can you clarify? I'll apply this patch, the problem above isn't strictly related to it. - Arnaldo