[igt-dev] [PATCH i-g-t] i915/gem_mmap_gtt: Increase concurrent stress

[Chris Wilson]

Rather than just try to look at the first fault of each mmap in each
thread, keep the threads running for the test duration and watch for
refaults.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/2012
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/i915/gem_mmap_gtt.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/tests/i915/gem_mmap_gtt.c b/tests/i915/gem_mmap_gtt.c
index 3a4681a18..79c242c68 100644
--- a/tests/i915/gem_mmap_gtt.c
+++ b/tests/i915/gem_mmap_gtt.c
@@ -1043,6 +1043,7 @@ test_write_cpu_read_gtt(int fd)
 struct thread_fault_concurrent {
 	pthread_t thread;
 	int id;
+	int *ctl;
 	uint32_t **ptr;
 };
 
@@ -1053,11 +1054,14 @@ thread_fault_concurrent(void *closure)
 	uint32_t val = 0;
 	int n;
 
-	for (n = 0; n < 32; n++) {
+	for (n = 0; READ_ONCE(t->ctl); n++) {
 		unsigned int id = (n + t->id) % 32;
 		uint32_t sz = *t->ptr[id] - 1;
 		int idx = rand() % sz + 1;
 
+		igt_assert(t->ptr[id][0]);
+		igt_assert(idx); /* avoid overwriting the size */
+
 		if (n & 1)
 			t->ptr[id][idx] = val;
 		else
@@ -1074,8 +1078,12 @@ test_fault_concurrent(int fd)
 {
 	uint32_t *ptr[32];
 	struct thread_fault_concurrent thread[64];
+	int *ctl;
 	int n;
 
+	ctl = create_pointer_size(fd, 4096);
+	*ctl = 1;
+
 	for (n = 0; n < 32; n++) {
 		uint32_t sz = (n + 1) << 19; /* 512KiB increments */
 
@@ -1083,19 +1091,25 @@ test_fault_concurrent(int fd)
 		*ptr[n] = sz / sizeof(uint32_t); /* num_elems for convenience */
 	}
 
+	__sync_synchronize();
 	for (n = 0; n < 64; n++) {
 		thread[n].ptr = ptr;
 		thread[n].id = n;
-		pthread_create(&thread[n].thread, NULL, thread_fault_concurrent, &thread[n]);
+		thread[n].ctl = ctl;
+		pthread_create(&thread[n].thread, NULL,
+				thread_fault_concurrent, &thread[n]);
 	}
 
 	sleep(2);
+	*ctl = 0;
 
+	__sync_synchronize();
 	for (n = 0; n < 64; n++)
 		pthread_join(thread[n].thread, NULL);
 
 	for (n = 0; n < 32; n++)
 		munmap(ptr[n], *ptr[n] * sizeof(uint32_t));
+	munmap(ctl, 4096);
 }
 
 static int mmap_ioctl(int i915, struct drm_i915_gem_mmap_gtt *arg)
-- 
2.27.0