[PATCH V4 07/15] selftests/resctrl: Remove "once" parameter required to be false

Reinette Chatre
2024-10-24T21:08:06Z

The CMT, MBM, and MBA tests rely on a benchmark that runs while
the test makes changes to needed configuration (for example memory
bandwidth allocation) and takes needed measurements. By default
the "fill_buf" benchmark is used and by default (via its
"once = false" setting) "fill_buf" is configured to run until
terminated after the test completes.

An unintended consequence of enabling the user to override the
benchmark also enables the user to change parameters to the
"fill_buf" benchmark. This enables the user to set "fill_buf" to
only cycle through the buffer once (by setting "once = true")
and thus breaking the CMT, MBA, and MBM tests that expect
workload/interference to be reflected by their measurements.

Prevent user space from changing the "once" parameter and ensure
that it is always false for the CMT, MBA, and MBM tests.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
Changes since V3:
- Add Ilpo's Reviewed-by tag.

Changes since V2:
- Remove unnecessary assignment to benchmark_cmd[5]. (Ilpo)

Changes since V1:
- New patch
---
tools/testing/selftests/resctrl/fill_buf.c | 7 ++++---
tools/testing/selftests/resctrl/resctrl.h | 2 +-
tools/testing/selftests/resctrl/resctrl_tests.c | 9 +++++++--
tools/testing/selftests/resctrl/resctrl_val.c | 11 +----------
4 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
index 34e5df721430..854f0108d8e6 100644
--- a/tools/testing/selftests/resctrl/fill_buf.c
+++ b/tools/testing/selftests/resctrl/fill_buf.c
@@ -151,7 +151,7 @@ unsigned char *alloc_buffer(size_t buf_size, int memflush)
return buf;
}

-int run_fill_buf(size_t buf_size, int memflush, int op, bool once)
+int run_fill_buf(size_t buf_size, int memflush, int op)
{
unsigned char *buf;

@@ -160,9 +160,10 @@ int run_fill_buf(size_t buf_size, int memflush, int op, bool once)
return -1;

if (op == 0)
- fill_cache_read(buf, buf_size, once);
+ fill_cache_read(buf, buf_size, false);
else
- fill_cache_write(buf, buf_size, once);
+ fill_cache_write(buf, buf_size, false);
+
free(buf);

return 0;
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 2dda56084588..51f5f4b25e06 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -142,7 +142,7 @@ int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
unsigned char *alloc_buffer(size_t buf_size, int 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 op, bool once);
+int run_fill_buf(size_t buf_size, int memflush, int op);
int initialize_mem_bw_imc(void);
int measure_mem_bw(const struct user_params *uparams,
struct resctrl_val_param *param, pid_t bm_pid,
diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
index ecbb7605a981..e7878077883f 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -266,8 +266,13 @@ int main(int argc, char **argv)
uparams.benchmark_cmd[1] = span_str;
uparams.benchmark_cmd[2] = "1";
uparams.benchmark_cmd[3] = "0";
- uparams.benchmark_cmd[4] = "false";
- uparams.benchmark_cmd[5] = NULL;
+ /*
+ * 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[4] = NULL;
}

ksft_set_plan(tests);
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index c9dd70ce3ea8..b0f3c594c4da 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -625,7 +625,6 @@ static void run_benchmark(int signum, siginfo_t *info, void *ucontext)
int operation, ret, memflush;
char **benchmark_cmd;
size_t span;
- bool once;
FILE *fp;

benchmark_cmd = info->si_ptr;
@@ -645,16 +644,8 @@ static void run_benchmark(int signum, siginfo_t *info, void *ucontext)
span = strtoul(benchmark_cmd[1], NULL, 10);
memflush = atoi(benchmark_cmd[2]);
operation = atoi(benchmark_cmd[3]);
- if (!strcmp(benchmark_cmd[4], "true")) {
- once = true;
- } else if (!strcmp(benchmark_cmd[4], "false")) {
- once = false;
- } else {
- ksft_print_msg("Invalid once parameter\n");
- parent_exit(ppid);
- }

- if (run_fill_buf(span, memflush, operation, once))
+ if (run_fill_buf(span, memflush, operation))
fprintf(stderr, "Error in running fill buffer\n");
} else {
/* Execute specified benchmark */
--
2.47.0