Re: [PATCH V2 09/13] selftests/resctrl: Make benchmark parameter passing robust

On Thu, 12 Sep 2024, Reinette Chatre wrote:

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

Changes since V1:

• Maintain original behavior where user can override "fill_buf" parameters via command line ... but only those that can actually be changed. (Ilpo)
• Fix parsing issues associated with original behavior to ensure any parameter is valid before any attempt to use it.
• Move patch earlier in series to highlight that this fixes existing issues.
• Make struct fill_buf_param dynamic to support user provided parameters as well as test specific parameters.
• Rewrite changelog.

---

tools/testing/selftests/resctrl/cmt_test.c | 32 ++---- tools/testing/selftests/resctrl/mba_test.c | 13 ++- tools/testing/selftests/resctrl/mbm_test.c | 22 ++-- tools/testing/selftests/resctrl/resctrl.h | 54 ++++++--- .../testing/selftests/resctrl/resctrl_tests.c | 104 +++++++++++++----- tools/testing/selftests/resctrl/resctrl_val.c | 43 ++++---- 6 files changed, 176 insertions(+), 92 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c index 0c045080d808..a7effe76b419 100644 --- a/tools/testing/selftests/resctrl/cmt_test.c +++ b/tools/testing/selftests/resctrl/cmt_test.c @@ -116,15 +116,13 @@ static void cmt_test_cleanup(void) static int cmt_run_test(const struct resctrl_test *test, const struct user_params *uparams) {

• const char * const *cmd = uparams->benchmark_cmd;
• const char *new_cmd[BENCHMARK_ARGS];

• struct fill_buf_param fill_buf = {0};

Empty initializer is enough to have the fields initialized to zero.

unsigned long cache_total_size = 0; int n = uparams->bits ? : 5; unsigned long long_mask;

• char *span_str = NULL; int count_of_bits; size_t span;
• int ret, i;

• int ret;

ret = get_full_cbm("L3", &long_mask); if (ret) @@ -155,32 +153,26 @@ static int cmt_run_test(const struct resctrl_test *test, const struct user_param span = cache_portion_size(cache_total_size, param.mask, long_mask);

• if (strcmp(cmd[0], "fill_buf") == 0) {

• /* Duplicate the command to be able to replace span in it */
  

• for (i = 0; uparams->benchmark_cmd[i]; i++)
  

• 	new_cmd[i] = uparams->benchmark_cmd[i];
  

• new_cmd[i] = NULL;
  

• ret = asprintf(&span_str, "%zu", span);
  

• if (ret < 0)
  

• 	return -1;
  

• new_cmd[1] = span_str;
  

• cmd = new_cmd;
  

• if (uparams->fill_buf) {

• fill_buf.buf_size = span;
  

• fill_buf.memflush = uparams->fill_buf->memflush;
  

• param.fill_buf = &fill_buf;
  

• } else if (!uparams->benchmark_cmd[0]) {

• fill_buf.buf_size = span;
  

• fill_buf.memflush = 1;
  

• param.fill_buf = &fill_buf;
  

  }

remove(RESULT_FILE_NAME);

• ret = resctrl_val(test, uparams, cmd, &param);

• ret = resctrl_val(test, uparams, &param); if (ret)

• goto out;
  

• return ret;
  

ret = check_results(&param, span, n); if (ret && (get_vendor() == ARCH_INTEL)) ksft_print_msg("Intel CMT may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n"); -out:

• free(span_str);
• return ret;

} diff --git a/tools/testing/selftests/resctrl/mba_test.c b/tools/testing/selftests/resctrl/mba_test.c index be0ead73e55d..7e43056c8737 100644 --- a/tools/testing/selftests/resctrl/mba_test.c +++ b/tools/testing/selftests/resctrl/mba_test.c @@ -172,11 +172,22 @@ static int mba_run_test(const struct resctrl_test *test, const struct user_param .setup = mba_setup, .measure = mba_measure, };

• struct fill_buf_param fill_buf = {0};

{}

int ret; remove(RESULT_FILE_NAME);

• ret = resctrl_val(test, uparams, uparams->benchmark_cmd, &param);

• if (uparams->fill_buf) {

• fill_buf.buf_size = uparams->fill_buf->buf_size;
  

• fill_buf.memflush = uparams->fill_buf->memflush;
  

• param.fill_buf = &fill_buf;
  

• } else if (!uparams->benchmark_cmd[0]) {

• fill_buf.buf_size = DEFAULT_SPAN;
  

• fill_buf.memflush = 1;
  

• param.fill_buf = &fill_buf;
  

• }
• ret = resctrl_val(test, uparams, &param); if (ret) return ret;

diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c index 9744bf1ac16f..b1f03a73333f 100644 --- a/tools/testing/selftests/resctrl/mbm_test.c +++ b/tools/testing/selftests/resctrl/mbm_test.c @@ -139,26 +139,26 @@ static int mbm_run_test(const struct resctrl_test *test, const struct user_param .setup = mbm_setup, .measure = mbm_measure, };

• char *endptr = NULL;
• size_t span = 0;

• struct fill_buf_param fill_buf = {0}; int ret;

remove(RESULT_FILE_NAME);

• if (uparams->benchmark_cmd[0] && strcmp(uparams->benchmark_cmd[0], "fill_buf") == 0) {

• if (uparams->benchmark_cmd[1]) {
  

• 	errno = 0;
  

• 	span = strtoul(uparams->benchmark_cmd[1], &endptr, 10);
  

• 	if (errno || uparams->benchmark_cmd[1] == endptr)
  

• 		return -errno;
  

• }
  

• if (uparams->fill_buf) {

• fill_buf.buf_size = uparams->fill_buf->buf_size;
  

• fill_buf.memflush = uparams->fill_buf->memflush;
  

• param.fill_buf = &fill_buf;
  

• } else if (!uparams->benchmark_cmd[0]) {

• fill_buf.buf_size = DEFAULT_SPAN;
  

• fill_buf.memflush = 1;
  

• param.fill_buf = &fill_buf;
  

  }

• ret = resctrl_val(test, uparams, uparams->benchmark_cmd, &param);

• ret = resctrl_val(test, uparams, &param); if (ret) return ret;

• ret = check_results(span);

• ret = check_results(param.fill_buf ? param.fill_buf->buf_size : 0); if (ret && (get_vendor() == ARCH_INTEL)) ksft_print_msg("Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");

diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h index 82801245e4c1..98462752cb46 100644 --- a/tools/testing/selftests/resctrl/resctrl.h +++ b/tools/testing/selftests/resctrl/resctrl.h @@ -43,16 +43,35 @@ #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 0 then the buffer will not be flushed after

• • 	allocation and initialization, otherwise the
    

• • 	buffer will be flushed. User can change value via
    

• • 	command line.
    

• */

+struct fill_buf_param {

• size_t buf_size;
• int memflush;

bool?

Or is there a plan to use other values than 0 and 1?

+};

/*

• 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 +106,29 @@ 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 { @@ -149,7 +176,6 @@ 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); diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c index 60627dbae20a..121079363208 100644 --- a/tools/testing/selftests/resctrl/resctrl_tests.c +++ b/tools/testing/selftests/resctrl/resctrl_tests.c @@ -148,6 +148,78 @@ static void run_single_test(const struct resctrl_test *test, const struct user_p test_cleanup(test); } +/*

• • Allocate and initialize a struct fill_buf_param with user provided
• • (via "-b fill_buf <fill_buf parameters>") parameters.
• • Use defaults (that may not be appropriate for all tests) for any
• • fill_buf parameters omitted by the user.
• • Historically it may have been possible for user space to provide
• • additional parameters, "operation" ("read" vs "write") in
• • benchmark_cmd[3] and "once" (run "once" or until terminated) in
• • benchmark_cmd[4]. Changing these parameters have never been
• • supported with the default of "read" operation and running until
• • terminated built into the tests. Any unsupported values for
• • (original) "fill_buf" parameters are treated as failure.
• • Return: On failure, forcibly exits the test on any parsing failure,

• •     returns NULL if no parsing needed (user did not actually provide
    

• •     "-b fill_buf").
    

• •     On success, returns pointer to newly allocated and fully
    

• •     initialized struct fill_buf_param that caller must free.
    

• */

+static struct fill_buf_param *alloc_fill_buf_param(struct user_params *uparams) +{

• struct fill_buf_param *fill_param = NULL;
• char *endptr = NULL;
• if (!uparams->benchmark_cmd[0] || strcmp(uparams->benchmark_cmd[0], "fill_buf"))

• return NULL;
  

• fill_param = malloc(sizeof(*fill_param));
• if (!fill_param)

• ksft_exit_skip("Unable to allocate memory for fill_buf parameters.\n");
  

• if (uparams->benchmark_cmd[1]) {

• errno = 0;
  

• fill_param->buf_size = strtoul(uparams->benchmark_cmd[1], &endptr, 10);
  

• if (errno || uparams->benchmark_cmd[1] == endptr) {
  

Should this also check that there is no extra garbage?

• 	free(fill_param);
  

• 	ksft_exit_skip("Unable to parse benchmark buffer size.\n");
  

• }
  

• } else {

• fill_param->buf_size = DEFAULT_SPAN;
  

• }
• if (uparams->benchmark_cmd[2]) {

• errno = 0;
  

• fill_param->memflush = strtol(uparams->benchmark_cmd[2], &endptr, 10);
  

• if (errno || uparams->benchmark_cmd[2] == endptr) {
  

Ditto ?

• 	free(fill_param);
  

• 	ksft_exit_skip("Unable to parse benchmark memflush parameter.\n");
  

• }
  

• } else {

• fill_param->memflush = 1;
  

memflush could be bool ?

• }
• if (uparams->benchmark_cmd[3]) {

• if (strcmp(uparams->benchmark_cmd[3], "0")) {
  

• 	free(fill_param);
  

• 	ksft_exit_skip("Only read operations supported.\n");
  

• }
  

• }
• if (uparams->benchmark_cmd[4]) {

• if (strcmp(uparams->benchmark_cmd[4], "false")) {
  

• 	free(fill_param);
  

• 	ksft_exit_skip("fill_buf is required to run until termination.\n");
  

• }
  

• }
• return fill_param;

+}

static void init_user_params(struct user_params *uparams) { memset(uparams, 0, sizeof(*uparams)); @@ -158,11 +230,11 @@ static void init_user_params(struct user_params *uparams) int main(int argc, char **argv) {

• struct fill_buf_param *fill_param = NULL; int tests = ARRAY_SIZE(resctrl_tests); bool test_param_seen = false; struct user_params uparams;

• char *span_str = NULL;
• int ret, c, i;

• int c, i;

init_user_params(&uparams); @@ -239,6 +311,10 @@ int main(int argc, char **argv) } last_arg:

• fill_param = alloc_fill_buf_param(&uparams);
• if (fill_param)

• uparams.fill_buf = fill_param;
  

• ksft_print_header();

/* @@ -257,33 +333,11 @@ int main(int argc, char **argv) filter_dmesg();

• if (!uparams.benchmark_cmd[0]) {

• /* If no benchmark is given by "-b" argument, use fill_buf. */
  

• uparams.benchmark_cmd[0] = "fill_buf";
  

• ret = asprintf(&span_str, "%u", DEFAULT_SPAN);
  

• if (ret < 0)
  

• 	ksft_exit_fail_msg("Out of memory!\n");
  

• uparams.benchmark_cmd[1] = span_str;
  

• uparams.benchmark_cmd[2] = "1";
  

• /*
  

•  * Third parameter was previously used for "operation"
  

•  * (read/write) of which only (now default) "read"/"0"
  

•  * works.
  

•  * Fourth parameter was previously used to indicate
  

•  * how long "fill_buf" should run for, with "false"
  

•  * ("fill_buf" will keep running until terminated)
  

•  * the only option that works.
  

•  */
  

• uparams.benchmark_cmd[3] = NULL;
  

• uparams.benchmark_cmd[4] = NULL;
  

• uparams.benchmark_cmd[5] = NULL;
  

• }
• ksft_set_plan(tests);

for (i = 0; i < ARRAY_SIZE(resctrl_tests); i++) run_single_test(resctrl_tests[i], &uparams);

• free(span_str);

• free(fill_param); ksft_finished();

} diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c index a1e097dc8e05..380c3f218d01 100644 --- a/tools/testing/selftests/resctrl/resctrl_val.c +++ b/tools/testing/selftests/resctrl/resctrl_val.c @@ -535,6 +535,11 @@ int measure_read_mem_bw(const struct user_params *uparams, return ret; } +struct benchmark_info {

• const struct user_params *uparams;
• struct resctrl_val_param *param;

+};

/*

• run_benchmark - Run a specified benchmark or fill_buf (default benchmark)

•    in specified signal. Direct benchmark stdio to /dev/null.
  

@@ -544,12 +549,15 @@ int measure_read_mem_bw(const struct user_params *uparams, */ static void run_benchmark(int signum, siginfo_t *info, void *ucontext) {

• char **benchmark_cmd;
• int ret, memflush;
• size_t span;

• struct benchmark_info *benchmark_info;
• const struct user_params *uparams;
• struct resctrl_val_param *param; FILE *fp;
• int ret;

• benchmark_cmd = info->si_ptr;

• benchmark_info = info->si_ptr;

I'd just assign this directly while defining the local variable.