112 lines
3.8 KiB
Diff
112 lines
3.8 KiB
Diff
From: Tom Zanussi <tom.zanussi@linux.intel.com>
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Date: Wed, 6 Dec 2017 16:38:10 -0600
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Subject: [PATCH 29/37] tracing: Add cpu field for hist triggers
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/older/patches-4.14.6-rt7.tar.xz
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A common key to use in a histogram is the cpuid - add a new cpu
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'synthetic' field named 'cpu' for that purpose.
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Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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Documentation/trace/histogram.txt | 15 +++++++++++++++
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kernel/trace/trace_events_hist.c | 28 +++++++++++++++++++++++++++-
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2 files changed, 42 insertions(+), 1 deletion(-)
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--- a/Documentation/trace/histogram.txt
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+++ b/Documentation/trace/histogram.txt
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@@ -172,6 +172,21 @@
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The examples below provide a more concrete illustration of the
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concepts and typical usage patterns discussed above.
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+ 'special' event fields
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+ ------------------------
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+
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+ There are a number of 'special event fields' available for use as
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+ keys or values in a hist trigger. These look like and behave as if
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+ they were actual event fields, but aren't really part of the event's
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+ field definition or format file. They are however available for any
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+ event, and can be used anywhere an actual event field could be.
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+ They are:
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+
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+ common_timestamp u64 - timestamp (from ring buffer) associated
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+ with the event, in nanoseconds. May be
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+ modified by .usecs to have timestamps
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+ interpreted as microseconds.
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+ cpu int - the cpu on which the event occurred.
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6.2 'hist' trigger examples
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---------------------------
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--- a/kernel/trace/trace_events_hist.c
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+++ b/kernel/trace/trace_events_hist.c
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@@ -227,6 +227,7 @@ enum hist_field_flags {
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HIST_FIELD_FL_VAR = 1 << 12,
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HIST_FIELD_FL_EXPR = 1 << 13,
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HIST_FIELD_FL_VAR_REF = 1 << 14,
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+ HIST_FIELD_FL_CPU = 1 << 15,
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};
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struct var_defs {
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@@ -1168,6 +1169,16 @@ static u64 hist_field_timestamp(struct h
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return ts;
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}
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+static u64 hist_field_cpu(struct hist_field *hist_field,
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+ struct tracing_map_elt *elt,
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+ struct ring_buffer_event *rbe,
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+ void *event)
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+{
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+ int cpu = smp_processor_id();
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+
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+ return cpu;
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+}
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+
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static struct hist_field *
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check_field_for_var_ref(struct hist_field *hist_field,
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struct hist_trigger_data *var_data,
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@@ -1619,6 +1630,8 @@ static const char *hist_field_name(struc
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field_name = hist_field_name(field->operands[0], ++level);
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else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
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field_name = "common_timestamp";
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+ else if (field->flags & HIST_FIELD_FL_CPU)
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+ field_name = "cpu";
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else if (field->flags & HIST_FIELD_FL_EXPR ||
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field->flags & HIST_FIELD_FL_VAR_REF) {
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if (field->system) {
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@@ -2124,6 +2137,15 @@ static struct hist_field *create_hist_fi
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goto out;
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}
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+ if (flags & HIST_FIELD_FL_CPU) {
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+ hist_field->fn = hist_field_cpu;
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+ hist_field->size = sizeof(int);
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+ hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
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+ if (!hist_field->type)
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+ goto free;
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+ goto out;
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+ }
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+
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if (WARN_ON_ONCE(!field))
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goto out;
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@@ -2358,7 +2380,9 @@ parse_field(struct hist_trigger_data *hi
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hist_data->enable_timestamps = true;
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if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
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hist_data->attrs->ts_in_usecs = true;
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- } else {
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+ } else if (strcmp(field_name, "cpu") == 0)
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+ *flags |= HIST_FIELD_FL_CPU;
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+ else {
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field = trace_find_event_field(file->event_call, field_name);
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if (!field || !field->size) {
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field = ERR_PTR(-EINVAL);
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@@ -4634,6 +4658,8 @@ static void hist_field_print(struct seq_
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if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
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seq_puts(m, "common_timestamp");
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+ else if (hist_field->flags & HIST_FIELD_FL_CPU)
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+ seq_puts(m, "cpu");
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else if (field_name) {
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if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
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seq_putc(m, '$');
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