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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT 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 65BCAC3A5A2 for ; Sat, 21 Sep 2019 00:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3277B217F5 for ; Sat, 21 Sep 2019 00:00:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="YPABTck2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407290AbfIUAAG (ORCPT ); Fri, 20 Sep 2019 20:00:06 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:38094 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407171AbfIUAAG (ORCPT ); Fri, 20 Sep 2019 20:00:06 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x8KNxZAW106774; Fri, 20 Sep 2019 23:59:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2019-08-05; bh=LhSuuZ1O24KLtZephMP5Prb2ILpveTttTiJkt7TPQqQ=; b=YPABTck2vDSA96rwpZ0JL7JjbUlwlEqcAH5A3bKBPr0zXIo+kAq+Vzrbdy7eBfGsS4RG CfEzIQmeDvPLBlFrwb6prBRRpC9IA9KKaUS/IQOVA4j4hDHunu8AB7zA1OLne+eDFRyE +pLoaW4/uvEJXuSkvtIN9jjDmC6NtYkpsfSh+TNslkTCDeF2LQz8/U98XhGvS34X3n9X hm5P6+58VtuNytyHjpFvXKpvXP0C17bhU+TKdSVRSrBkYySKN32l4UdbePVepIQFaj/5 mNGwq7KQ7IlUviPKknnGAY/7nzI6J3Nm3ezft75WhzXgaEtdtyS7f86HpmE9sGwSLCM1 ag== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 2v3vb555cd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 20 Sep 2019 23:59:35 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x8KNwhX7125912; Fri, 20 Sep 2019 23:59:35 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3030.oracle.com with ESMTP id 2v51vr3pva-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 20 Sep 2019 23:59:34 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x8KNxXd9006426; Fri, 20 Sep 2019 23:59:33 GMT Received: from ca-common-hq.us.oracle.com (/10.211.9.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 20 Sep 2019 16:59:33 -0700 From: Divya Indi To: Steven Rostedt , linux-kernel@vger.kernel.org Cc: Divya Indi , Joe Jin , Srinivas Eeda , Aruna Ramakrishna , Manjunath Patil Subject: [RFC]Sample module for Kernel access to Ftrace instances. Date: Fri, 20 Sep 2019 16:59:25 -0700 Message-Id: <1569023966-23004-1-git-send-email-divya.indi@oracle.com> X-Mailer: git-send-email 1.8.3.1 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9386 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=821 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909200203 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9386 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=882 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909200203 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [PATCH] tracing: Sample module to demonstrate kernel access to Ftrace Hi, This patch is for a sample module to demonstrate the use of APIs that were introduced/exported in order to access Ftrace instances from within the kernel. Please Note: This module is dependent on - - commit: f45d122 tracing: Kernel access to Ftrace instances - Patches pending review: https://lore.kernel.org/lkml/1565805327-579-1-git-send-email-divya.indi@oracle.com/ The sample module creates/lookup a trace array called sample-instance on module load time. We then start a kernel thread(simple-thread) to - 1) Enable tracing for event "sample_event" to buffer associated with the trace array - "sample-instance". 2) Start a timer that will disable tracing to this buffer after 5 sec. (Tracing disabled after 5 sec ie at count=4) 3) Write to the buffer using trace_array_printk() 4) Stop the kernel thread and destroy the buffer during module unload. A sample output for the same - # tracer: nop # # entries-in-buffer/entries-written: 16/16 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | sample-instance-26797 [003] .... 955180.489833: simple_thread: trace_array_printk: count=0 sample-instance-26797 [003] .... 955180.489836: sample_event: count value=0 at jiffies=5249940864 sample-instance-26797 [003] .... 955181.513722: simple_thread: trace_array_printk: count=1 sample-instance-26797 [003] .... 955181.513724: sample_event: count value=1 at jiffies=5249941888 sample-instance-26797 [003] .... 955182.537629: simple_thread: trace_array_printk: count=2 sample-instance-26797 [003] .... 955182.537631: sample_event: count value=2 at jiffies=5249942912 sample-instance-26797 [003] .... 955183.561516: simple_thread: trace_array_printk: count=3 sample-instance-26797 [003] .... 955183.561518: sample_event: count value=3 at jiffies=5249943936 sample-instance-26797 [003] .... 955184.585423: simple_thread: trace_array_printk: count=4 sample-instance-26797 [003] .... 955184.585427: sample_event: count value=4 at jiffies=5249944960 sample-instance-26797 [003] .... 955185.609344: simple_thread: trace_array_printk: count=5 sample-instance-26797 [003] .... 955186.633241: simple_thread: trace_array_printk: count=6 sample-instance-26797 [003] .... 955187.657157: simple_thread: trace_array_printk: count=7 sample-instance-26797 [003] .... 955188.681039: simple_thread: trace_array_printk: count=8 sample-instance-26797 [003] .... 955189.704937: simple_thread: trace_array_printk: count=9 sample-instance-26797 [003] .... 955190.728840: simple_thread: trace_array_printk: count=10 Let me know if you have any questions. Thanks, Divya