linux-kernel - [PATCH v5 2/4] tracing: Add cpu as a key field in histogram

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Date:   Fri,  2 Sep 2016 18:07:29 +0530
From:   Binoy Jayan <binoy.jayan@...aro.org>
To:     "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Daniel Wagner <daniel.wagner@...-carit.de>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Masami <masami.hiramatsu@...aro.org>,
        Binoy Jayan <binoy.jayan@...aro.org>
Subject: [PATCH v5 2/4] tracing: Add cpu as a key field in histogram

The field 'cpu' although part of the set of generic fields, is not made
part of the key fields when mentioned in the trigger command. This hack
suggested by Daniel marks it as one of the key fields and make it appear
in the histogram output.

Signed-off-by: Binoy Jayan <binoy.jayan@...aro.org>
---
 kernel/trace/trace_events.c      |  3 ++-
 kernel/trace/trace_events_hist.c | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 03c0a48..c395608 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -152,7 +152,8 @@ EXPORT_SYMBOL_GPL(trace_define_field);
 
 #define __generic_field(type, item, filter_type)			\
 	ret = __trace_define_field(&ftrace_generic_fields, #type,	\
-				   #item, 0, 0, is_signed_type(type),	\
+				   #item, 0, sizeof(type),              \
+				   is_signed_type(type),                \
 				   filter_type);			\
 	if (ret)							\
 		return ret;
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 0c05b8a..4e0a12e 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -75,6 +75,11 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event)
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
 
+static u64 hist_field_cpu(struct hist_field *hist_field, void *event)
+{
+	return (u64) raw_smp_processor_id();
+}
+
 #define DEFINE_HIST_FIELD_FN(type)					\
 static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
 {									\
@@ -119,6 +124,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_SYSCALL		= 128,
 	HIST_FIELD_FL_STACKTRACE	= 256,
 	HIST_FIELD_FL_LOG2		= 512,
+	HIST_FIELD_FL_CPU		= 1024,
 };
 
 struct hist_trigger_attrs {
@@ -371,6 +377,11 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 		goto out;
 	}
 
+	if (flags & HIST_FIELD_FL_CPU) {
+		hist_field->fn = hist_field_cpu;
+		goto out;
+	}
+
 	if (WARN_ON_ONCE(!field))
 		goto out;
 
@@ -526,6 +537,9 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 	} else {
 		char *field_name = strsep(&field_str, ".");
 
+		if (strcmp(field_name, "cpu") == 0)
+			flags |= HIST_FIELD_FL_CPU;
+
 		if (field_str) {
 			if (strcmp(field_str, "hex") == 0)
 				flags |= HIST_FIELD_FL_HEX;
@@ -556,6 +570,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 			key_size = MAX_FILTER_STR_VAL;
 		else
 			key_size = field->size;
+
 	}
 
 	hist_data->fields[key_idx] = create_hist_field(field, flags);
-- 
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