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Date: Mon, 5 Sep 2016 07:40:27 +0200
From: Daniel Wagner <daniel.wagner@...-carit.de>
To: Binoy Jayan <binoy.jayan@...aro.org>,
"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
CC: Ingo Molnar <mingo@...hat.com>, Arnd Bergmann <arnd@...db.de>,
<linux-kernel@...r.kernel.org>,
Masami <masami.hiramatsu@...aro.org>
Subject: Re: [PATCH v5 2/4] tracing: Add cpu as a key field in histogram
Hi Binoy
On 09/02/2016 02:37 PM, Binoy Jayan wrote:
> 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.
While you are at it, why not adding the COMM as well? I know there is
already the common_pid.execname. With only a few extra lines we get COMM
as well and it allows to write something like
hist:key=cpu,comm:sort=cpu,comm
for example.
cheers,
daniel
>From cc2f610078ebe9ba8d850cbf602aa529df690cdb Mon Sep 17 00:00:00 2001
From: Daniel Wagner <daniel.wagner@...-carit.de>
Date: Wed, 31 Aug 2016 09:37:38 +0200
Subject: [PATCH] tracing: Add hist trigger support for generic fields
Whenever a trace is printed the generic fields (CPU, COMM) are
reconstructed (see trace_print_context()). CPU is taken from the
trace_iterator and COMM is extracted from the savedcmd map (see
__trace_find_cmdline()).
We can't reconstruct this information for hist events. Therefore this
information needs to stored when a new event is added to the hist
buffer.
There is already support for extracting the COMM for the common_pid
field. For this the tracing_map_ops infrasture is used. Unfortantly, we
can't reuse it because it extends an existing hist_field. That means we
first need to add a hist_field before we are able to make reuse of
trace_map_ops.
Furthermore, it is quite easy to extend the current code to support
those two fields by adding hist_field_cpu() and hist_field_comm().
Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc: Binoy Jayan <binoy.jayan@...aro.org>
---
kernel/trace/trace.h | 6 ++++++
kernel/trace/trace_events.c | 13 +++++++------
kernel/trace/trace_events_hist.c | 31 ++++++++++++++++++++++++++++---
3 files changed, 41 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f783df4..2b8889b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1288,6 +1288,12 @@ static inline bool is_function_field(struct ftrace_event_field *field)
return field->filter_type == FILTER_TRACE_FN;
}
+static inline bool is_generic_field(struct ftrace_event_field *field)
+{
+ return field->filter_type == FILTER_CPU ||
+ field->filter_type == FILTER_COMM;
+}
+
extern enum regex_type
filter_parse_regex(char *buff, int len, char **search, int *not);
extern void print_event_filter(struct trace_event_file *file,
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 03c0a48..7d9154d 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -150,9 +150,10 @@ int trace_define_field(struct trace_event_call *call, const char *type,
}
EXPORT_SYMBOL_GPL(trace_define_field);
-#define __generic_field(type, item, filter_type) \
+#define __generic_field(type, item, filter_type, size) \
ret = __trace_define_field(&ftrace_generic_fields, #type, \
- #item, 0, 0, is_signed_type(type), \
+ #item, 0, size, \
+ is_signed_type(type), \
filter_type); \
if (ret) \
return ret;
@@ -170,10 +171,10 @@ static int trace_define_generic_fields(void)
{
int ret;
- __generic_field(int, CPU, FILTER_CPU);
- __generic_field(int, cpu, FILTER_CPU);
- __generic_field(char *, COMM, FILTER_COMM);
- __generic_field(char *, comm, FILTER_COMM);
+ __generic_field(int, CPU, FILTER_CPU, sizeof(int));
+ __generic_field(int, cpu, FILTER_CPU, sizeof(int));
+ __generic_field(char *, COMM, FILTER_COMM, TASK_COMM_LEN + 1);
+ __generic_field(char *, comm, FILTER_COMM, TASK_COMM_LEN + 1);
return ret;
}
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f3a960e..0b40f22 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -75,6 +75,16 @@ 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) smp_processor_id();
+}
+
+static u64 hist_field_comm(struct hist_field *hist_field, void *event)
+{
+ return (u64)(unsigned long)current->comm;
+}
+
#define DEFINE_HIST_FIELD_FN(type) \
static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
{ \
@@ -119,6 +129,7 @@ enum hist_field_flags {
HIST_FIELD_FL_SYSCALL = 128,
HIST_FIELD_FL_STACKTRACE = 256,
HIST_FIELD_FL_LOG2 = 512,
+ HIST_FIELD_FL_COMM = 1024,
};
struct hist_trigger_attrs {
@@ -383,6 +394,13 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
hist_field->fn = hist_field_dynstring;
else
hist_field->fn = hist_field_pstring;
+ } else if (is_generic_field(field)) {
+ if (field->filter_type == FILTER_CPU)
+ hist_field->fn = hist_field_cpu;
+ else if (field->filter_type == FILTER_COMM) {
+ flags |= HIST_FIELD_FL_COMM;
+ hist_field->fn = hist_field_comm;
+ }
} else {
hist_field->fn = select_value_fn(field->size,
field->is_signed);
@@ -748,7 +766,8 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
cmp_fn = tracing_map_cmp_none;
- else if (is_string_field(field))
+ else if (is_string_field(field) ||
+ hist_field->flags & HIST_FIELD_FL_COMM)
cmp_fn = tracing_map_cmp_string;
else
cmp_fn = tracing_map_cmp_num(field->size,
@@ -871,7 +890,8 @@ static inline void add_to_key(char *compound_key, void *key,
/* ensure NULL-termination */
if (size > key_field->size - 1)
size = key_field->size - 1;
- }
+ } else if (key_field->flags & HIST_FIELD_FL_COMM)
+ size = key_field->field->size;
memcpy(compound_key + key_field->offset, key, size);
}
@@ -906,7 +926,8 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
key = entries;
} else {
field_contents = key_field->fn(key_field, rec);
- if (key_field->flags & HIST_FIELD_FL_STRING) {
+ if (key_field->flags & (HIST_FIELD_FL_STRING |
+ HIST_FIELD_FL_COMM)) {
key = (void *)(unsigned long)field_contents;
use_compound_key = true;
} else
@@ -1004,6 +1025,10 @@ hist_trigger_entry_print(struct seq_file *m,
} else if (key_field->flags & HIST_FIELD_FL_STRING) {
seq_printf(m, "%s: %-50s", key_field->field->name,
(char *)(key + key_field->offset));
+ } else if (key_field->flags & HIST_FIELD_FL_COMM) {
+ seq_printf(m, "%s: %-16s",
+ key_field->field->name,
+ (char *)(key + key_field->offset));
} else {
uval = *(u64 *)(key + key_field->offset);
seq_printf(m, "%s: %10llu", key_field->field->name,
--
2.7.4
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