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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 CDBDCC33CB1 for ; Sun, 19 Jan 2020 14:15:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9080420730 for ; Sun, 19 Jan 2020 14:15:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579443351; bh=g6W+x/faFHqWNP96zz8T9b7ZL6BY5dXLLnKV7Hf3XO8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=LrCsQKdIG7UO07XYdV47vOMgUUdiexqx9ZbUytw56fQbXUk2V6HSjwwWwLdSKcobe +stiT5rNPYfLJVRYOeZwuSIwjDOuruTAH8661JguSOwiftTEjFXFm/lrwWG7sHI0xM 3Sc0duTfEbbZ6dOxoJ6zAsHDO9QqIOzxt0sudED4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726982AbgASOPr (ORCPT ); Sun, 19 Jan 2020 09:15:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:45704 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726816AbgASOPr (ORCPT ); Sun, 19 Jan 2020 09:15:47 -0500 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 321B9206D7; Sun, 19 Jan 2020 14:15:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579443345; bh=g6W+x/faFHqWNP96zz8T9b7ZL6BY5dXLLnKV7Hf3XO8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HY1pepszUjHeQ7PAcS8Jl2iWG1LldgGGs0i5pq/mkN2LUjpK1pk4uq4KHR3O1btxo Vta+93TAlQtTDnHppuZ4qoNbFTa+a2g/nH/Lr2Ud+U2TLuX721CnHa4sj0JqjEKwB+ k8LRmsrQ06qjSRtoR7kl6aJFvLaDAVM8oSRGsfD0= Date: Sun, 19 Jan 2020 23:15:40 +0900 From: Masami Hiramatsu To: Randy Dunlap Cc: Steven Rostedt , Ingo Molnar , Frank Rowand , Namhyung Kim , Tim Bird , Jiri Olsa , Arnaldo Carvalho de Melo , Tom Zanussi , Rob Herring , Andrew Morton , Thomas Gleixner , Greg Kroah-Hartman , Alexey Dobriyan , Jonathan Corbet , Linus Torvalds , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 22/22] Documentation: tracing: Add boot-time tracing document Message-Id: <20200119231540.eaebef64f8a69bc97f4abf25@kernel.org> In-Reply-To: References: <157867220019.17873.13377985653744804396.stgit@devnote2> <157867246028.17873.8047384554383977870.stgit@devnote2> X-Mailer: Sylpheed 3.5.1 (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-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Randy, Thank you for your comments! On Sat, 18 Jan 2020 10:14:08 -0800 Randy Dunlap wrote: > Hi, > > Here are a few editorial comments for you... > > > On 1/10/20 8:07 AM, Masami Hiramatsu wrote: > > Add a documentation about boot-time tracing options in > > boot config. > > > > Signed-off-by: Masami Hiramatsu > > --- > > Documentation/admin-guide/bootconfig.rst | 2 > > Documentation/trace/boottime-trace.rst | 184 ++++++++++++++++++++++++++++++ > > Documentation/trace/index.rst | 1 > > 3 files changed, 187 insertions(+) > > create mode 100644 Documentation/trace/boottime-trace.rst > > > > > diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst > > new file mode 100644 > > index 000000000000..1d10fdebf1b2 > > --- /dev/null > > +++ b/Documentation/trace/boottime-trace.rst > > @@ -0,0 +1,184 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +================= > > +Boot-time tracing > > +================= > > + > > +:Author: Masami Hiramatsu > > + > > +Overview > > +======== > > + > > +Boot-time tracing allows users to trace boot-time process including > > +device initialization with full features of ftrace including per-event > > +filter and actions, histograms, kprobe-events and synthetic-events, > > +and trace instances. > > +Since kernel cmdline is not enough to control these complex features, > > +this uses bootconfig file to describe tracing feature programming. > > + > > +Options in the Boot Config > > +========================== > > + > > +Here is the list of available options list for boot time tracing in > > +boot config file [1]_. All options are under "ftrace." or "kernel." > > +refix. See kernel parameters for the options which starts > > prefix. Oops, OK. > > > +with "kernel." prefix [2]_. > > + > > +.. [1] See :ref:`Documentation/admin-guide/bootconfig.rst ` > > +.. [2] See :ref:`Documentation/admin-guide/kernel-parameters.rst ` > > + > > +Ftrace Global Options > > +--------------------- > > + > > +Ftrace global options have "kernel." prefix in boot config, which means > > +these options are passed as a part of kernel legacy command line. > > + > > +kernel.tp_printk > > + Output trace-event data on printk buffer too. > > + > > +kernel.dump_on_oops [= MODE] > > + Dump ftrace on Oops. If MODE = 1 or omitted, dump trace buffer > > + on all CPUs. If MODE = 2, dump a buffer on a CPU which kicks Oops. > > + > > +kernel.traceoff_on_warning > > + Stop tracing if WARN_ON() occurs. > > + > > +kernel.fgraph_max_depth = MAX_DEPTH > > + Set MAX_DEPTH to maximum depth of fgraph tracer. > > + > > +kernel.fgraph_filters = FILTER[, FILTER2...] > > + Add fgraph tracing function filters. > > + > > +kernel.fgraph_notraces = FILTER[, FILTER2...] > > + Add fgraph non tracing function filters. > > non-tracing OK. > > > + > > + > > +Ftrace Per-instance Options > > +--------------------------- > > + > > +These options can be used for each instance including global ftrace node. > > + > > +ftrace.[instance.INSTANCE.]options = OPT1[, OPT2[...]] > > + Enable given ftrace options. > > + > > +ftrace.[instance.INSTANCE.]trace_clock = CLOCK > > + Set given CLOCK to ftrace's trace_clock. > > + > > +ftrace.[instance.INSTANCE.]buffer_size = SIZE > > + Configure ftrace buffer size to SIZE. You can use "KB" or "MB" > > + for that SIZE. > > + > > +ftrace.[instance.INSTANCE.]alloc_snapshot > > + Allocate snapshot buffer. > > + > > +ftrace.[instance.INSTANCE.]cpumask = CPUMASK > > + Set CPUMASK as trace cpu-mask. > > + > > +ftrace.[instance.INSTANCE.]events = EVENT[, EVENT2[...]] > > + Enable given events on boot. You can use a wild card in EVENT. > > + > > +ftrace.[instance.INSTANCE.]tracer = TRACER > > + Set TRACER to current tracer on boot. (e.g. function) > > + > > +ftrace.[instance.INSTANCE.]ftrace.filters > > + This will take an array of tracing function filter rules > > end with '.' as above descriptions. Yes, I missed it. > > > + > > +ftrace.[instance.INSTANCE.]ftrace.notraces > > + This will take an array of NON-tracing function filter rules > > ditto OK. > > > + > > + > > +Ftrace Per-Event Options > > +------------------------ > > + > > +These options are setting per-event options. > > + > > +ftrace.[instance.INSTANCE.]event.GROUP.EVENT.enable > > + Enables GROUP:EVENT tracing. > > Enable OK. > > > + > > +ftrace.[instance.INSTANCE.]event.GROUP.EVENT.filter = FILTER > > + Set FILTER rule to the GROUP:EVENT. > > + > > +ftrace.[instance.INSTANCE.]event.GROUP.EVENT.actions = ACTION[, ACTION2[...]] > > + Set ACTIONs to the GROUP:EVENT. > > + > > +ftrace.[instance.INSTANCE.]event.kprobes.EVENT.probes = PROBE[, PROBE2[...]] > > + Defines new kprobe event based on PROBEs. It is able to define > > + multiple probes on one event, but those must have same type of > > + arguments. This option is available only for the event which > > + group name is "kprobes". > > + > > +ftrace.[instance.INSTANCE.]event.synthetic.EVENT.fields = FIELD[, FIELD2[...]] > > + Defines new synthetic event with FIELDs. Each field should be > > + "type varname". > > + > > +Note that kprobe and synthetic event definitions can be written under > > +instance node, but those are also visible from other instances. So please > > +take care for event name conflict. > > + > > + > > +Examples > > +======== > > + > > +For example, to add filter and actions for each event, define kprobe > > +events, and synthetic events with histogram, write a boot config like > > +below:: > > + > > + ftrace.event { > > + task.task_newtask { > > + filter = "pid < 128" > > + enable > > + } > > + kprobes.vfs_read { > > + probes = "vfs_read $arg1 $arg2" > > + filter = "common_pid < 200" > > + enable > > + } > > + synthetic.initcall_latency { > > + fields = "unsigned long func", "u64 lat" > > + actions = "hist:keys=func.sym,lat:vals=lat:sort=lat" > > + } > > + initcall.initcall_start { > > + actions = "hist:keys=func:ts0=common_timestamp.usecs" > > + } > > + initcall.initcall_finish { > > + actions = "hist:keys=func:lat=common_timestamp.usecs-$ts0:onmatch(initcall.initcall_start).initcall_latency(func,$lat)" > > + } > > + } > > + > > +Also, boottime tracing supports "instance" node, which allows us to run > > boot-time [for consistency] OK. > > > +several tracers for different purpose at once. For example, one tracer > > +is for tracing functions start with "user\_", and others tracing "kernel\_" > > starting OK. > > > +functions, you can write boot config as below:: > > + > > + ftrace.instance { > > + foo { > > + tracer = "function" > > + ftrace.filters = "user_*" > > + } > > + bar { > > + tracer = "function" > > + ftrace.filters = "kernel_*" > > + } > > + } > > + > > +The instance node also accepts event nodes so that each instance > > +can customize its event tracing. > > + > > +This boot-time tracing also supports ftrace kernel parameters via boot > > +config. > > +For example, following kernel parameters:: > > + > > + trace_options=sym-addr trace_event=initcall:* tp_printk trace_buf_size=1M ftrace=function ftrace_filter="vfs*" > > + > > +This can be written in boot config like below:: > > + > > + kernel { > > + trace_options = sym-addr > > + trace_event = "initcall:*" > > + tp_printk > > + trace_buf_size = 1M > > + ftrace = function > > + ftrace_filter = "vfs*" > > + } > > + > > +Note that parameters start with "kernel" prefix instead of "ftrace". > > HTH. Very helpful. Thanks! -- Masami Hiramatsu