From patchwork Mon Dec 21 06:02:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tzvetomir Stoyanov (VMware)" X-Patchwork-Id: 11984253 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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 7DC3AC43381 for ; Mon, 21 Dec 2020 06:03:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59A6222513 for ; Mon, 21 Dec 2020 06:03:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727566AbgLUGD6 (ORCPT ); Mon, 21 Dec 2020 01:03:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727670AbgLUGD5 (ORCPT ); Mon, 21 Dec 2020 01:03:57 -0500 Received: from mail-ed1-x531.google.com (mail-ed1-x531.google.com [IPv6:2a00:1450:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29F57C0611CB for ; Sun, 20 Dec 2020 22:03:00 -0800 (PST) Received: by mail-ed1-x531.google.com with SMTP id c7so8456586edv.6 for ; Sun, 20 Dec 2020 22:03:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5GZNYh356HhEcIbSlefkqNxXutdLhcij5aCTg2yE2II=; b=OOu9G1N2Ngbo7GeJyj7bZ10neJjiIn1F4udsLj79TmDadjVsAB0ivDh1T6UL1gyiGZ 55iSwoWnqy58LU02bJcZuHafFW8ErVIvFkUuGMz1Ps4bnKRCSwep5fmoCQv/k5qV6V5e jQHNjmAjoYdwuqNsobnGO7OHKzs+BNpLKyWW7QDS8IkatyI0l79RKKEFIjAR2qXgTnt0 wsTBuwunIRdR2QbGvyApPh5pe3IXgQQ2Wdee8apfjEsEMR++kWP2rD3bPZ26Dk3ma/pw RpR0ZqNJFF+rlFnkOgyWnpc9QiQJxolVHc3rfvz64njdazV6MvZrDCgc7hnRM0r1jTjg O8dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5GZNYh356HhEcIbSlefkqNxXutdLhcij5aCTg2yE2II=; b=HT/glIEpWUnoADoomPyjLhwhx31BhvZTmeUp2AqzpaZDLCrQ86P8f/tfnpPGhwJzl4 kM2pu4/BI/COKlIJ5/oGhg5WbRMKTwx8qTTu5PnnHci7Ic3kuKsntBYXLLCm4pklqKtM kFGBbVDHogwcKJzwF5LYXz0x+uy0N28rxe61vK1/FYbGxe/AXk+EReJnWp1tZNxmj1VQ 1364w6gCv/tM89RFYF3D1nqqDciOtj5YEi+HL7y8o2Avjhcfn3eQbF1RI+k4MvWFgCFn B0W0sB4URbuKCGIdmeOdIHyyTaHVVd/mbic442yDW+h846hHB0Yw20L4l1ausiMbQk/j iGKw== X-Gm-Message-State: AOAM532GeI/rxqwqvvVMvuLfF1k68KwnYr+wVZteQaOiJqSGiCzXyEe4 wU/PDzVyZE3BTATxHhuOzS0= X-Google-Smtp-Source: ABdhPJyL4jkks0W5LxtMxW0vS0iwIw4ffjnz4Fn6OEalAXCTBYBsXjA5Oa5f9BqFRYUzjODLP4hzZQ== X-Received: by 2002:a05:6402:a45:: with SMTP id bt5mr14721203edb.130.1608530578840; Sun, 20 Dec 2020 22:02:58 -0800 (PST) Received: from oberon.zico.biz ([83.222.187.186]) by smtp.gmail.com with ESMTPSA id z10sm8560885ejl.30.2020.12.20.22.02.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Dec 2020 22:02:58 -0800 (PST) From: "Tzvetomir Stoyanov (VMware)" To: rostedt@goodmis.org Cc: linux-trace-devel@vger.kernel.org Subject: [PATCH v2 3/8] libtracefs man pages: APIs for working with trace systems and events. Date: Mon, 21 Dec 2020 08:02:47 +0200 Message-Id: <20201221060252.177890-4-tz.stoyanov@gmail.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201221060252.177890-1-tz.stoyanov@gmail.com> References: <20201221060252.177890-1-tz.stoyanov@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Documented APIs: tracefs_event_systems() tracefs_system_events() tracefs_iterate_raw_events() Signed-off-by: Tzvetomir Stoyanov (VMware) --- Documentation/libtracefs-events.txt | 143 ++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 Documentation/libtracefs-events.txt diff --git a/Documentation/libtracefs-events.txt b/Documentation/libtracefs-events.txt new file mode 100644 index 0000000..3a51055 --- /dev/null +++ b/Documentation/libtracefs-events.txt @@ -0,0 +1,143 @@ +libtracefs(3) +============= + +NAME +---- +tracefs_event_systems, tracefs_system_events, tracefs_iterate_raw_events - +Work with trace systems and events. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +char pass:[*]pass:[*]*tracefs_event_systems*(const char pass:[*]_tracing_dir_); +char pass:[*]pass:[*]*tracefs_system_events*(const char pass:[*]_tracing_dir_, const char pass:[*]_system_); +int *tracefs_iterate_raw_events*(struct tep_handle pass:[*]_tep_, struct tracefs_instance pass:[*]_instance_, cpu_set_t pass:[*]_cpus_, int _cpu_size_, int (pass:[*]_callback_)(struct tep_event pass:[*], struct tep_record pass:[*], int, void pass:[*]), void pass:[*]_callback_context_); + +-- + +DESCRIPTION +----------- +Trace systems and events related APIs. + +The _tracefs_event_systems()_ function returns array of strings with the +names of all registered trace systems, located in the given _tracing_dir_ +directory. This could be NULL or the location of the tracefs mount point +for the trace systems of the local machine, or it may be a path to a copy +of the tracefs directory from another machine. The last entry in the array +is a NULL pointer. The array must be freed with _tracefs_list_free()_ API. + +The _tracefs_system_events()_ function returns array of strings with the +names of all registered trace events for given trace system specified by +_system_, located in the given _tracing_dir_ directory. This could be NULL +or the location of the tracefs mount point for the trace systems of the +local machine, or it may be a path to a copy of the tracefs directory +from another machine. The last entry in the array as a NULL pointer. +The array must be freed with _tracefs_list_free()_ API. + +The _tracefs_interate_raw_events()_ function will read the tracefs raw +data buffers and call the specified _callback_ function for every event it +encounters. An initialized _tep_ handler is required (See +_tracefs_local_events_(3)). If _instance_ is NULL, then the toplevel +tracefs buffer is used, otherwise the buffer for the corresponding +_instance_ is read. To filter only on a subset of CPUs, _cpus_ and +_cpu_size_ may be set to only call _callback_ with events that occurred on +the CPUs specified, otherwise if _cpus_ is NULL then the _callback_ +function will be called for all events, and _cpu_size_ is ignored. The +_callback_ function will be called with the following parameters: A +pointer to a struct tep_event that corresponds to the type of event the +record is; The record representing the event; The CPU that the event +occurred on; and a pointer to user specified _context_. If the _callback_ +returns non-zero, the iteration stops. + + +RETURN VALUE +------------ +The _tracefs_event_systems()_ and __tracefs_system_events()_ functions return +an array of strings. The last element in that array is a NULL pointer. The array +must be freed with _tracefs_list_free()_ API. In case of an error, NULL is returned. + +The _tracefs_iterate_raw_events()_ function returns -1 in case of an error or +0 otherwise. + +EXAMPLE +------- +[source,c] +-- +#include + +char **systems = tracefs_event_systems(NULL); + + if (systems) { + int i = 0; + /* Got registered trace systems from the top trace instance */ + while (systems[i]) { + char **events = tracefs_system_events(NULL, systems[i]); + if (events) { + /* Got registered events in system[i] from the top trace instance */ + int j = 0; + + while (events[j]) { + /* Got event[j] in system[i] from the top trace instance */ + j++; + } + tracefs_list_free(events); + } + i++; + } + tracefs_list_free(systems); + } +.... +static int records_walk(struct tep_event *tep, struct tep_record *record, int cpu, void *context) +{ + /* Got recorded event on cpu */ + return 0; +} +... +struct tep_event *tep = tracefs_local_events(NULL); + + if (!tep) { + /* Failed to initialise tep handler with local events */ + ... + } + if (tracefs_iterate_raw_events(tep, NULL, NULL, 0, records_walk, NULL) < 0) { + /* Error walking through the recorded raw events */ + } + tep_free(tep); +-- +FILES +----- +[verse] +-- +*tracefs.h* + Header file to include in order to have access to the library APIs. +*-ltracefs* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +_libtracefs(3)_, +_libtraceevent(3)_, +_trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* +*Tzvetomir Stoyanov* +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtracefs is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ \ No newline at end of file