[PATCH i-g-t v1 2/3] tests/intel/xe_pmu: Check if other processes are using the DRM device

[Soham Purkait <soham.purkait@intel.com>]

If the engine accuracy test is run with other processes using the DRM
device, the GPU engine activity may be higher than expected. Which may
lead to false positives in the test, even if the engine activity is
reported correctly.
To help identify this issue, a check for other processes using the DRM
device is provided and a warning message is printed if any such processes
are found and the very test is skipped.

Signed-off-by: Soham Purkait <soham.purkait@intel.com>
---
 tests/intel/xe_pmu.c | 25 +++++++++++++++++++++++++
 tests/meson.build    |  1 +
 2 files changed, 26 insertions(+)

diff --git a/tests/intel/xe_pmu.c b/tests/intel/xe_pmu.c
index fb4b871e7..4dd610e8c 100644
--- a/tests/intel/xe_pmu.c
+++ b/tests/intel/xe_pmu.c
@@ -95,6 +95,7 @@
  */
 
 #include "igt.h"
+#include "igt_drm_clients.h"
 #include "igt_perf.h"
 #include "igt_sriov_device.h"
 #include "igt_sysfs.h"
@@ -507,6 +508,30 @@ static void accuracy(int fd, struct drm_xe_engine_class_instance *eci,
 	uint64_t config, before[2], after[2];
 	int link[2], pmu_fd[2];
 	double engine_activity, expected;
+	unsigned long wait = 100000;
+	struct igt_drm_client_proc *procs = NULL;
+	int num_clients = 0;
+
+	/* Wait for other processes using the DRM device ends */
+	for (int pass = 0; pass < 50; pass++) {
+		if (!igt_drm_get_client_procs(fd, getpid(), NULL))
+			break;
+		usleep(wait);
+	}
+
+	num_clients = igt_drm_get_client_procs(fd, getpid(), &procs);
+
+	/* Check if still any process is using the DRM device */
+	if (num_clients) {
+		for (unsigned int i = 0; i < num_clients; i++) {
+			igt_warn("%s (pid=%u client=%lu) is using DRM device.\n",
+				 procs[i].print_name, procs[i].pid, procs[i].id);
+		}
+		free(procs);
+		procs = NULL;
+		igt_skip("As other processes are using the DRM device, "
+			 "cannot ensure the reliability of this test.\n");
+	}
 
 	cycle_us = min_test_us / target_iter;
 	active_us = cycle_us * target_percentage / 100;
diff --git a/tests/meson.build b/tests/meson.build
index 79f21c018..d13598fdd 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -422,6 +422,7 @@ extra_dependencies = {
 	'sw_sync': [ libatomic ],
 	'xe_fault_injection': [ lib_igt_xe_oa ],
 	'xe_oa': [ lib_igt_xe_oa ],
+	'xe_pmu': [ lib_igt_drm_clients ],
         'xe_compute': [ igt_deps,lib_igt_perf,lib_igt_profiling,math ],
 }
 
-- 
2.43.0