From: Tom Zanussi <tom.zanussi@linux.intel.com>
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, fengguang.wu@intel.com,
linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
Tom Zanussi <tom.zanussi@linux.intel.com>
Subject: [PATCH v7 34/37] tracing: Add a clock attribute for hist triggers
Date: Wed, 6 Dec 2017 16:38:15 -0600 [thread overview]
Message-ID: <85eadef67603d5e8e72581dbbb49ff4702edb7f8.1512593081.git.tom.zanussi@linux.intel.com> (raw)
In-Reply-To: <cover.1512593081.git.tom.zanussi@linux.intel.com>
In-Reply-To: <cover.1512593081.git.tom.zanussi@linux.intel.com>
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 <tom.zanussi@linux.intel.com>
Signed-off-by: Rajvi Jingar <rajvi.jingar@intel.com>
---
Documentation/trace/histogram.txt | 11 +++++++++-
kernel/trace/trace_events_hist.c | 42 ++++++++++++++++++++++++++++++++++++---
2 files changed, 49 insertions(+), 4 deletions(-)
diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt
index df08882..6e05510 100644
--- a/Documentation/trace/histogram.txt
+++ b/Documentation/trace/histogram.txt
@@ -1671,7 +1671,16 @@ features have been added to the hist trigger support:
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 1309a8f..b0b10f3 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;
@@ -1792,6 +1793,7 @@ 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);
}
@@ -1847,6 +1849,19 @@ 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);
@@ -1911,6 +1926,14 @@ 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);
@@ -4935,6 +4958,8 @@ 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);
@@ -5202,7 +5227,6 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
data->paused = true;
if (named_data) {
- destroy_hist_data(data->private_data);
data->private_data = named_data->private_data;
set_named_trigger_data(data, named_data);
data->ops = &event_hist_trigger_named_ops;
@@ -5214,10 +5238,22 @@ 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);
+ }
+
+ if (named_data)
+ destroy_hist_data(hist_data);
+
+ ret++;
out:
return ret;
}
--
1.9.3
next prev parent reply other threads:[~2017-12-06 22:41 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-06 22:37 [PATCH v7 00/37] tracing: Inter-event (e.g. latency) support Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 01/37] tracing: Move hist trigger Documentation to histogram.txt Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 02/37] tracing: Add Documentation for log2 modifier Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 03/37] tracing: Add support to detect and avoid duplicates Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 04/37] tracing: Remove code which merges duplicates Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 05/37] ring-buffer: Add interface for setting absolute time stamps Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 06/37] ring-buffer: Redefine the unimplemented RINGBUF_TYPE_TIME_STAMP Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 07/37] tracing: Add timestamp_mode trace file Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 08/37] tracing: Give event triggers access to ring_buffer_event Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 09/37] tracing: Add ring buffer event param to hist field functions Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 10/37] tracing: Break out hist trigger assignment parsing Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 11/37] tracing: Add hist trigger timestamp support Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 12/37] tracing: Add per-element variable support to tracing_map Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 13/37] tracing: Add hist_data member to hist_field Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 14/37] tracing: Add usecs modifier for hist trigger timestamps Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 15/37] tracing: Add variable support to hist triggers Tom Zanussi
2017-12-08 13:02 ` Namhyung Kim
2017-12-08 19:54 ` Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 16/37] tracing: Account for variables in named trigger compatibility Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 17/37] tracing: Move get_hist_field_flags() Tom Zanussi
2017-12-06 22:37 ` [PATCH v7 18/37] tracing: Add simple expression support to hist triggers Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 19/37] tracing: Generalize per-element hist trigger data Tom Zanussi
2017-12-08 13:06 ` Namhyung Kim
2017-12-08 19:56 ` Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 20/37] tracing: Pass tracing_map_elt to hist_field accessor functions Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 21/37] tracing: Add hist_field 'type' field Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 22/37] tracing: Add variable reference handling to hist triggers Tom Zanussi
2017-12-11 15:17 ` Namhyung Kim
2017-12-11 17:53 ` Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 23/37] tracing: Add hist trigger action hook Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 24/37] tracing: Add support for 'synthetic' events Tom Zanussi
2017-12-12 14:42 ` Namhyung Kim
2017-12-12 16:07 ` Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 25/37] tracing: Add support for 'field variables' Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 26/37] tracing: Add 'onmatch' hist trigger action support Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 27/37] tracing: Add 'onmax' " Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 28/37] tracing: Allow whitespace to surround hist trigger filter Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 29/37] tracing: Add cpu field for hist triggers Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 30/37] tracing: Add hist trigger support for variable reference aliases Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 31/37] tracing: Add 'last error' error facility for hist triggers Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 32/37] tracing: Add inter-event hist trigger Documentation Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 33/37] tracing: Make tracing_set_clock() non-static Tom Zanussi
2017-12-06 22:38 ` Tom Zanussi [this message]
2017-12-06 22:38 ` [PATCH v7 35/37] tracing: Increase trace_recursive_lock() limit for synthetic events Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 36/37] tracing: Add inter-event blurb to HIST_TRIGGERS config option Tom Zanussi
2017-12-06 22:38 ` [PATCH v7 37/37] selftests: ftrace: Add inter-event hist triggers testcases Tom Zanussi
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