selftests/resctrl: Make benchmark parameter passing robust

The benchmark used during the CMT, MBM, and MBA tests can be provided by
the user via (-b) parameter, if not provided the default "fill_buf"
benchmark is used. The user is additionally able to override
any of the "fill_buf" default parameters when running the tests with
"-b fill_buf <fill_buf parameters>".

The "fill_buf" parameters are managed as an array of strings. Using an
array of strings is complex because it requires transformations to/from
strings at every producer and consumer. This is made worse for the
individual tests where the default benchmark parameters values may not
be appropriate and additional data wrangling is required. For example,
the CMT test duplicates the entire array of strings in order to replace
one of the parameters.

More issues appear when combining the usage of an array of strings with
the use case of user overriding default parameters by specifying
"-b fill_buf <parameters>". This use case is fragile with opportunities
to trigger a SIGSEGV because of opportunities for NULL pointers to exist
in the array of strings. For example, by running below (thus by specifying
"fill_buf" should be used but all parameters are NULL):
	$ sudo resctrl_tests -t mbm -b fill_buf

Replace the "array of strings" parameters used for "fill_buf" with
new struct fill_buf_param that contains the "fill_buf" parameters that
can be used directly without transformations to/from strings. Two
instances of struct fill_buf_param may exist at any point in time:
	* If the user provides new parameters to "fill_buf", the
	  user parameter structure (struct user_params) will point to a
	  fully initialized and immutable struct fill_buf_param
	  containing the user provided parameters.
	* If "fill_buf" is the benchmark that should be used by a test,
	  then the test parameter structure (struct resctrl_val_param)
	  will point to a fully initialized struct fill_buf_param. The
	  latter may contain (a) the user provided parameters verbatim,
	  (b) user provided parameters adjusted to be appropriate for
	  the test, or (c) the default parameters for "fill_buf" that
	  is appropriate for the test if the user did not provide
	  "fill_buf" parameters nor an alternate benchmark.

The existing behavior of CMT test is to use test defined value for the
buffer size even if the user provides another value via command line.
This behavior is maintained since the test requires that the buffer size
matches the size of the cache allocated, and the amount of cache
allocated can instead be changed by the user with the "-n" command line
parameter.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 43 insertions, 16 deletions

diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 82801245e4c1..c9336f9c2cae 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -44,15 +44,35 @@
 #define DEFAULT_SPAN		(250 * MB)
 
 /*
+ * fill_buf_param:	"fill_buf" benchmark parameters
+ * @buf_size:		Size (in bytes) of buffer used in benchmark.
+ *			"fill_buf" allocates and initializes buffer of
+ *			@buf_size. User can change value via command line.
+ * @memflush:		If false the buffer will not be flushed after
+ *			allocation and initialization, otherwise the
+ *			buffer will be flushed. User can change value via
+ *			command line (via integers with 0 interpreted as
+ *			false and anything else as true).
+ */
+struct fill_buf_param {
+	size_t		buf_size;
+	bool		memflush;
+};
+
+/*
  * user_params:		User supplied parameters
  * @cpu:		CPU number to which the benchmark will be bound to
  * @bits:		Number of bits used for cache allocation size
  * @benchmark_cmd:	Benchmark command to run during (some of the) tests
+ * @fill_buf:		Pointer to user provided parameters for "fill_buf",
+ *			NULL if user did not provide parameters and test
+ *			specific defaults should be used.
  */
 struct user_params {
 	int cpu;
 	int bits;
 	const char *benchmark_cmd[BENCHMARK_ARGS];
+	const struct fill_buf_param *fill_buf;
 };
 
 /*
@@ -87,21 +107,29 @@ struct resctrl_test {
  * @init:		Callback function to initialize test environment
  * @setup:		Callback function to setup per test run environment
  * @measure:		Callback that performs the measurement (a single test)
+ * @fill_buf:		Parameters for default "fill_buf" benchmark.
+ *			Initialized with user provided parameters, possibly
+ *			adapted to be relevant to the test. If user does
+ *			not provide parameters for "fill_buf" nor a
+ *			replacement benchmark then initialized with defaults
+ *			appropriate for test. NULL if user provided
+ *			benchmark.
  */
 struct resctrl_val_param {
-	const char	*ctrlgrp;
-	const char	*mongrp;
-	char		filename[64];
-	unsigned long	mask;
-	int		num_of_runs;
-	int		(*init)(const struct resctrl_val_param *param,
-				int domain_id);
-	int		(*setup)(const struct resctrl_test *test,
-				 const struct user_params *uparams,
-				 struct resctrl_val_param *param);
-	int		(*measure)(const struct user_params *uparams,
-				   struct resctrl_val_param *param,
-				   pid_t bm_pid);
+	const char		*ctrlgrp;
+	const char		*mongrp;
+	char			filename[64];
+	unsigned long		mask;
+	int			num_of_runs;
+	int			(*init)(const struct resctrl_val_param *param,
+					int domain_id);
+	int			(*setup)(const struct resctrl_test *test,
+					 const struct user_params *uparams,
+					 struct resctrl_val_param *param);
+	int			(*measure)(const struct user_params *uparams,
+					   struct resctrl_val_param *param,
+					   pid_t bm_pid);
+	struct fill_buf_param	*fill_buf;
 };
 
 struct perf_event_read {
@@ -138,10 +166,10 @@ int write_schemata(const char *ctrlgrp, char *schemata, int cpu_no,
 int write_bm_pid_to_resctrl(pid_t bm_pid, const char *ctrlgrp, const char *mongrp);
 int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
 		    int group_fd, unsigned long flags);
-unsigned char *alloc_buffer(size_t buf_size, int memflush);
+unsigned char *alloc_buffer(size_t buf_size, bool memflush);
 void mem_flush(unsigned char *buf, size_t buf_size);
 void fill_cache_read(unsigned char *buf, size_t buf_size, bool once);
-int run_fill_buf(size_t buf_size, int memflush);
+int run_fill_buf(size_t buf_size, bool memflush);
 int initialize_read_mem_bw_imc(void);
 int measure_read_mem_bw(const struct user_params *uparams,
 			struct resctrl_val_param *param, pid_t bm_pid);
@@ -149,7 +177,6 @@ void initialize_mem_bw_resctrl(const struct resctrl_val_param *param,
 			       int domain_id);
 int resctrl_val(const struct resctrl_test *test,
 		const struct user_params *uparams,
-		const char * const *benchmark_cmd,
 		struct resctrl_val_param *param);
 unsigned long create_bit_mask(unsigned int start, unsigned int len);
 unsigned int count_contiguous_bits(unsigned long val, unsigned int *start);