Re: [PATCH 06/12] perf trace/scripting: add Python scripting engine

[Tom Zanussi <tzanussi@gmail.com>]

On Mon, 2010-02-22 at 03:27 +0100, Frederic Weisbecker wrote:
> On Wed, Jan 27, 2010 at 02:27:57AM -0600, Tom Zanussi wrote:
> > +static void define_value(enum print_arg_type field_type,
> > +			 const char *ev_name,
> > +			 const char *field_name,
> > +			 const char *field_value,
> > +			 const char *field_str)
> > +{
> > +	const char *handler_name = "define_flag_value";
> > +	PyObject *handler, *t, *retval;
> > +	unsigned long long value;
> > +	unsigned n = 0;
> > +
> > +	if (field_type == PRINT_SYMBOL)
> > +		handler_name = "define_symbolic_value";
> > +
> > +	t = PyTuple_New(MAX_FIELDS);
> > +	if (!t)
> > +		Py_FatalError("couldn't create Python tuple");
> > +
> > +	value = eval_flag(field_value);
> > +
> > +	PyTuple_SetItem(t, n++, PyString_FromString(ev_name));
> > +	PyTuple_SetItem(t, n++, PyString_FromString(field_name));
> > +	PyTuple_SetItem(t, n++, PyInt_FromLong(value));
> > +	PyTuple_SetItem(t, n++, PyString_FromString(field_str));
> > +
> > +	if (_PyTuple_Resize(&t, n) == -1)
> > +		Py_FatalError("error resizing Python tuple");
> 
> 
> 
> Why are creating a tuple of 64 fields while you are always using
> 4?
> 
> 
> 
> > +
> > +	handler = PyDict_GetItemString(main_dict, handler_name);
> > +	if (handler && PyCallable_Check(handler)) {
> > +		retval = PyObject_CallObject(handler, t);
> > +		if (retval == NULL)
> > +			handler_call_die(handler_name);
> > +	}
> > +
> > +	Py_DECREF(t);
> > +}
> > +
> > +
> 
> [...]
> 
> > +static void define_field(enum print_arg_type field_type,
> > +			 const char *ev_name,
> > +			 const char *field_name,
> > +			 const char *delim)
> > +{
> > +	const char *handler_name = "define_flag_field";
> > +	PyObject *handler, *t, *retval;
> > +	unsigned n = 0;
> > +
> > +	if (field_type == PRINT_SYMBOL)
> > +		handler_name = "define_symbolic_field";
> > +
> > +	t = PyTuple_New(MAX_FIELDS);
> > +	if (!t)
> > +		Py_FatalError("couldn't create Python tuple");
> > +
> > +	PyTuple_SetItem(t, n++, PyString_FromString(ev_name));
> > +	PyTuple_SetItem(t, n++, PyString_FromString(field_name));
> > +	if (field_type == PRINT_FLAGS)
> > +		PyTuple_SetItem(t, n++, PyString_FromString(delim));
> > +
> > +	if (_PyTuple_Resize(&t, n) == -1)
> > +		Py_FatalError("error resizing Python tuple");
> 
> 
> 
> Same here (except you may or may not have a PRINT_FLAGS type).
> 

Good point - no reason to resize if we don't have to.  Here's a patch to
change that.

Thanks,

Tom

[PATCH] perf trace/scripting: remove unnecessary PyTuple resizes

If we know the size of a tuple in advance, there's no need to resize
it - start out with the known size in the first place.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
---
 .../util/scripting-engines/trace-event-python.c    |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index d402f64..33a414b 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -68,7 +68,7 @@ static void define_value(enum print_arg_type field_type,
 	if (field_type == PRINT_SYMBOL)
 		handler_name = "define_symbolic_value";
 
-	t = PyTuple_New(MAX_FIELDS);
+	t = PyTuple_New(4);
 	if (!t)
 		Py_FatalError("couldn't create Python tuple");
 
@@ -79,9 +79,6 @@ static void define_value(enum print_arg_type field_type,
 	PyTuple_SetItem(t, n++, PyInt_FromLong(value));
 	PyTuple_SetItem(t, n++, PyString_FromString(field_str));
 
-	if (_PyTuple_Resize(&t, n) == -1)
-		Py_FatalError("error resizing Python tuple");
-
 	handler = PyDict_GetItemString(main_dict, handler_name);
 	if (handler && PyCallable_Check(handler)) {
 		retval = PyObject_CallObject(handler, t);
@@ -116,7 +113,10 @@ static void define_field(enum print_arg_type field_type,
 	if (field_type == PRINT_SYMBOL)
 		handler_name = "define_symbolic_field";
 
-	t = PyTuple_New(MAX_FIELDS);
+	if (field_type == PRINT_FLAGS)
+		t = PyTuple_New(3);
+	else
+		t = PyTuple_New(2);
 	if (!t)
 		Py_FatalError("couldn't create Python tuple");
 
@@ -125,9 +125,6 @@ static void define_field(enum print_arg_type field_type,
 	if (field_type == PRINT_FLAGS)
 		PyTuple_SetItem(t, n++, PyString_FromString(delim));
 
-	if (_PyTuple_Resize(&t, n) == -1)
-		Py_FatalError("error resizing Python tuple");
-
 	handler = PyDict_GetItemString(main_dict, handler_name);
 	if (handler && PyCallable_Check(handler)) {
 		retval = PyObject_CallObject(handler, t);
-- 
1.6.4.GIT