From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753082AbdJ3Uyf (ORCPT ); Mon, 30 Oct 2017 16:54:35 -0400 Received: from mga02.intel.com ([134.134.136.20]:60479 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752786AbdJ3Uyb (ORCPT ); Mon, 30 Oct 2017 16:54:31 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,321,1505804400"; d="scan'208";a="144007590" From: Tom Zanussi To: rostedt@goodmis.org Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, bigeasy@linutronix.de, joel.opensrc@gmail.com, joelaf@google.com, mathieu.desnoyers@efficios.com, baohong.liu@intel.com, rajvi.jingar@intel.com, julia@ni.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Tom Zanussi Subject: [PATCH v4 34/37] tracing: Add a clock attribute for hist triggers Date: Mon, 30 Oct 2017 15:52:16 -0500 Message-Id: <3682e8f9c1288db19482c1a02609705cd83b3c6b.1509395596.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The default clock if timestamps are used in a histogram is "global". If timestamps aren't used, the clock is irrelevant. Use the "clock=" param only if you want to override the default "global" clock for a histogram with timestamps. Signed-off-by: Tom Zanussi Signed-off-by: Rajvi Jingar --- Documentation/trace/histogram.txt | 11 ++++++++++- kernel/trace/trace_events_hist.c | 38 ++++++++++++++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 3 deletions(-) diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt index 0eea8b9..aa450bb 100644 --- a/Documentation/trace/histogram.txt +++ b/Documentation/trace/histogram.txt @@ -1674,7 +1674,16 @@ features have been added to the hist trigger support: default it is in units of nanoseconds; appending '.usecs' to a common_timestamp field changes the units to microseconds. -These features are decribed in more detail in the following sections. +A note on inter-event timestamps: If $common_timestamp is used in a +histogram, the trace buffer is automatically switched over to using +absolute timestamps and the "global" trace clock, in order to avoid +bogus timestamp differences with other clocks that aren't coherent +across CPUs. This can be overridden by specifying one of the other +trace clocks instead, using the "clock=XXX" hist trigger attribute, +where XXX is any of the clocks listed in the tracing/trace_clock +pseudo-file. + +These features are described in more detail in the following sections. 2.2.1 Histogram Variables ------------------------- diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index acebaae..686fbca 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -242,6 +242,7 @@ struct hist_trigger_attrs { char *vals_str; char *sort_key_str; char *name; + char *clock; bool pause; bool cont; bool clear; @@ -1790,6 +1791,7 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs) kfree(attrs->sort_key_str); kfree(attrs->keys_str); kfree(attrs->vals_str); + kfree(attrs->clock); kfree(attrs); } @@ -1845,6 +1847,19 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs) ret = -ENOMEM; goto out; } + } else if (strncmp(str, "clock=", strlen("clock=")) == 0) { + strsep(&str, "="); + if (!str) { + ret = -EINVAL; + goto out; + } + + str = strstrip(str); + attrs->clock = kstrdup(str, GFP_KERNEL); + if (!attrs->clock) { + ret = -ENOMEM; + goto out; + } } else if (strncmp(str, "size=", strlen("size=")) == 0) { int map_bits = parse_map_size(str); @@ -1908,6 +1923,14 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str) goto free; } + if (!attrs->clock) { + attrs->clock = kstrdup("global", GFP_KERNEL); + if (!attrs->clock) { + ret = -ENOMEM; + goto free; + } + } + return attrs; free: destroy_hist_trigger_attrs(attrs); @@ -4917,6 +4940,8 @@ static int event_hist_trigger_print(struct seq_file *m, seq_puts(m, ".descending"); } seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits)); + if (hist_data->enable_timestamps) + seq_printf(m, ":clock=%s", hist_data->attrs->clock); print_actions_spec(m, hist_data); @@ -5179,10 +5204,19 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops, goto out; } - ret++; + if (hist_data->enable_timestamps) { + char *clock = hist_data->attrs->clock; + + ret = tracing_set_clock(file->tr, hist_data->attrs->clock); + if (ret) { + hist_err("Couldn't set trace_clock: ", clock); + goto out; + } - if (hist_data->enable_timestamps) tracing_set_time_stamp_abs(file->tr, true); + } + + ret++; out: return ret; } -- 1.9.3