Re: [PATCH i-g-t v4 2/2] test/intel/xe_bo_alloc: Add oversubscribe concurrent bind stress subtest

Add test for oversubscribing VRAM in multi process environment that
creates VM, bind large BOs and submit workloads nearly simultaneously.

Previous coverage lacked a scenario combining multi-process bind
with VRAM oversubscription. This generates memory pressure with
multi-process VM Bind activity and concurrent submission, exercising
the bind pipeline under eviction pressure.

v3: Fixed minor nits

Signed-off-by: Sobin Thomas <redacted>
---
  tests/intel/xe_bo_alloc.c | 498 ++++++++++++++++++++++++++++++++++++++
  1 file changed, 498 insertions(+)

diff --git a/tests/intel/xe_bo_alloc.c b/tests/intel/xe_bo_alloc.c
index 58380463c..06cd651eb 100644
--- a/tests/intel/xe_bo_alloc.c
+++ b/tests/intel/xe_bo_alloc.c

@@ -29,6 +29,19 @@
  #define THREAD_VA_STRIDE GB(1)
  #define SZ_4K_SHIFT	12
  #define MAX_ALLOCATIONS 50000
+#define INT_ADD_CNT 4
+#define TIMEOUT_NS (30ULL * 1000000000ULL)
+#define MAX_SRAM_TEST_SIZE GB(32)
+#define GPR_RX_ADDR(x)          (0x600 + (x) * 8)
+#define MAX_PROCS 20
+
+#define EXEC_DATA_ADDR		0x100000ULL
+#define EXEC_RESULT_ADDR	0x200000ULL
+#define EXEC_BATCH_ADDR		0x300000ULL
+#define EXEC_UFENCE_ADDR	0x400000ULL
+#define STRESS_BIND_ADDR	0x40000000ULL
+
+
  
  /**
   * SUBTEST: all-sizes-once

@@ -75,14 +88,48 @@
   * Description: Test 50 random BO allocation sizes in test table with a thread per engine,
   * leak the binding, unaligned bind addresses
   * Test category: stress test
+ *
+ * SUBTEST: test_vm_oversubscribe_concurrent_bind
+ * Description: Test enough random BO allocation sizes, bound as arrays of binds, to trigger
+ * evictions with 2 processes per engine, leak the BO munmap / gem close, unaligned bind addresses
+ * Test category: stress test
   */
  
  #define GB(x) (1024ULL * 1024ULL * 1024ULL * (x))
  #define MIN_BUFS_PER_PROC 2
  
  #define N_ALLOC_SIZES	256
+#define USER_FENCE_VALUE 0xdeadbeefdeadbeefull
+
  static uint64_t *alloc_sizes;
  
+struct gem_bo {
+	uint32_t handle;
+	uint64_t size;
+	uint32_t *ptr;
+	uint64_t addr;
+};
+
+struct xe_oversubscribe_ctx {
+	uint32_t vm_id;
+	uint32_t exec_queue_id;
+};
+
+struct mem_bind_sync {
+	struct gem_bo *bufs;
+	int n_bufs;
+	uint64_t *binds_ufence;
+};
+
+struct process_data {
+	pthread_mutex_t mutex;
+	pthread_cond_t cond;
+	int ready;
+	int failed;
+	pthread_barrier_t barrier;
+	bool go;
+};
+
  /*
   * Data-driven subtest matrix.
   *

@@ -103,6 +150,7 @@ enum test_type {
  	TYPE_SINGLE,
  	TYPE_ARRAY_BIND,
  	TYPE_THREAD,
+	TYPE_OVERSUBSCRIBE,
  };
  
  struct test_case {

@@ -223,6 +271,450 @@ static int __xe_vm_bind_array(int fd, uint32_t vm,
  	return 0;
  }
  
+static void init_pdata(struct process_data *pdata)
+{
+	pthread_mutexattr_t mattr;
+	pthread_condattr_t cattr;
+
+	pthread_mutexattr_init(&mattr);
+	igt_assert_eq(pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED), 0);
+	igt_assert_eq(pthread_mutex_init(&pdata->mutex, &mattr), 0);
+	pthread_mutexattr_destroy(&mattr);
+
+	pthread_condattr_init(&cattr);
+	igt_assert_eq(pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED), 0);
+	igt_assert_eq(pthread_cond_init(&pdata->cond, &cattr), 0);
+	pthread_condattr_destroy(&cattr);
+	pdata->ready = 0;
+	pdata->failed = 0;
+	pdata->go = false;
+}
+
+static void process_ready_and_wait(struct process_data *pdata)
+{
+	pthread_mutex_lock(&pdata->mutex);
+	pdata->ready++;
+	pthread_cond_broadcast(&pdata->cond);
+	while (!pdata->go)
+		pthread_cond_wait(&pdata->cond, &pdata->mutex);
+	pthread_mutex_unlock(&pdata->mutex);
+}
+
+static void process_setup_failed(struct process_data *pdata)
+{
+	pthread_mutex_lock(&pdata->mutex);
+	pdata->failed++;
+	pthread_cond_broadcast(&pdata->cond);
+	pthread_mutex_unlock(&pdata->mutex);
+}
+
+static void release_ready_processes(struct process_data *pdata, int n_proc)
+{
+	pthread_mutex_lock(&pdata->mutex);
+	/*
+	 * Wait until all children have either reached VM Bind rendevouz
+	 * Or, failed setup and exited the test path.
+	 */
+	while (pdata->ready + pdata->failed < n_proc)
+		pthread_cond_wait(&pdata->cond, &pdata->mutex);
+
+	igt_debug(" Process rendezvous: ready=%d failed=%d total = %d\n",
+		  pdata->ready, pdata->failed, n_proc);
+
+	/* Release every successful child into VM_Bind at same time*/
+	pdata->go = true;
+	pthread_cond_broadcast(&pdata->cond);
+	pthread_mutex_unlock(&pdata->mutex);
+}
+
+static int build_add_batch(struct gem_bo *batch_bo, struct gem_bo *integers_bo,
+			   struct gem_bo *result_bo, int ints_to_add)
+{
+	int pos = 0;
+	int i;
+	uint64_t tmp_addr;
+
+	batch_bo->ptr[pos++] = MI_LOAD_REGISTER_MEM_CMD | MI_LRI_LRM_CS_MMIO | 2;
+	batch_bo->ptr[pos++] = GPR_RX_ADDR(0);
+	tmp_addr = integers_bo->addr + 0 * sizeof(uint32_t);
+	batch_bo->ptr[pos++] = tmp_addr & 0xFFFFFFFF;
+	batch_bo->ptr[pos++] = (tmp_addr >> 32) & 0xFFFFFFFF;
+	for (i = 1; i < ints_to_add; i++) {
+		/* r1 = integers_bo[i] */
+		batch_bo->ptr[pos++] = MI_LOAD_REGISTER_MEM_CMD | MI_LRI_LRM_CS_MMIO | 2;
+		batch_bo->ptr[pos++] = GPR_RX_ADDR(1);
+		tmp_addr = integers_bo->addr + i * sizeof(uint32_t);
+		batch_bo->ptr[pos++] = tmp_addr & 0xFFFFFFFF;
+		batch_bo->ptr[pos++] = (tmp_addr >> 32) & 0xFFFFFFFF;
+		/* r0 = r0 + r1 */
+		batch_bo->ptr[pos++] = MI_MATH(4);
+		batch_bo->ptr[pos++] = MI_MATH_LOAD(MI_MATH_REG_SRCA, MI_MATH_REG(0));
+		batch_bo->ptr[pos++] = MI_MATH_LOAD(MI_MATH_REG_SRCB, MI_MATH_REG(1));
+		batch_bo->ptr[pos++] = MI_MATH_ADD;
+		batch_bo->ptr[pos++] = MI_MATH_STORE(MI_MATH_REG(0), MI_MATH_REG_ACCU);
+	}
+	/* result_bo[0] = r0 */
+	batch_bo->ptr[pos++] = MI_STORE_REGISTER_MEM_GEN8 | MI_LRI_LRM_CS_MMIO;
+	batch_bo->ptr[pos++] = GPR_RX_ADDR(0);
+	tmp_addr = result_bo->addr + 0 * sizeof(uint32_t);
+	batch_bo->ptr[pos++] = tmp_addr & 0xFFFFFFFF;
+	batch_bo->ptr[pos++] = (tmp_addr >> 32) & 0xFFFFFFFF;
+
+	batch_bo->ptr[pos++] = MI_BATCH_BUFFER_END;
+	while (pos % 4 != 0)
+		batch_bo->ptr[pos++] = MI_NOOP;
+	return pos;
+}
+
+static void create_exec_queue(int fd, struct xe_oversubscribe_ctx *ctx)
+{
+	ctx->exec_queue_id = xe_exec_queue_create(fd, ctx->vm_id,
+						  &xe_engine(fd, 0)->instance, 0);
+}
+
+static uint64_t *
+vm_bind_bo_batch(int fd, struct xe_oversubscribe_ctx *ctx, struct gem_bo *bos, int size,
+		 int *out_err)
+{
+	uint64_t *ufence;
+	struct drm_xe_sync bind_sync;
+	struct drm_xe_vm_bind_op *binds;
+	int i;
+
+	binds = calloc(size, sizeof(*binds));
+	igt_assert(binds);
+
+	ufence = calloc(1, sizeof(*ufence));
+	igt_assert(ufence);
+	bind_sync = (struct drm_xe_sync) {
+		.type = DRM_XE_SYNC_TYPE_USER_FENCE,
+		.flags = DRM_XE_SYNC_FLAG_SIGNAL,
+		.addr = to_user_pointer(ufence),
+		.timeline_value = 1,
+	};
+
+	for (i = 0; i < size; i++) {
+		binds[i] = (struct drm_xe_vm_bind_op) {
+			.obj = bos[i].handle,
+			.obj_offset = 0,
+			.range = bos[i].size,
+			.addr = bos[i].addr,
+			.op = DRM_XE_VM_BIND_OP_MAP,
+			.flags = 0,
+		};
+	}
+	*out_err = __xe_vm_bind_array(fd, ctx->vm_id, binds, size, &bind_sync, 1);
+	free(binds);
+	return ufence;
+}
+
+static int fill_random_integers(struct gem_bo *int_bo, int ints_to_add)
+{
+	uint32_t expected_result = 0;
+	char expr[256];
+	int len = 0;
+
+	for (int i = 0; i < ints_to_add; i++) {
+		uint32_t random_int = rand() % 8;
+
+		int_bo->ptr[i] = random_int;
+		expected_result += random_int;
+
+		len += snprintf(expr + len, sizeof(expr) - len, "%s%u",
+				i ? " + " : "", random_int);
+	}
+	igt_debug("%s = %u\n", expr, expected_result);
+	return expected_result;
+}
+
+static void cleanup_bo_resources(int fd, struct gem_bo *bo)
+{
+	if (bo->ptr) {
+		igt_assert_eq(munmap(bo->ptr, bo->size), 0);
+		bo->ptr = NULL;
+	}
+	if (bo->handle)
+		gem_close(fd, bo->handle);
+}
+
+static int create_test_bos(int fd, struct xe_oversubscribe_ctx *ctx,
+			   struct mem_bind_sync *bind, uint32_t placement,
+			   uint64_t *addr)
+{
+	const char *mem_type = (placement & vram_memory(fd, 0)) ? "VRAM" : "SRAM";
+	int ret;
+
+	for (int i = 0; i < bind->n_bufs; i++) {
+		struct gem_bo *bo = &bind->bufs[i];
+
+		bo->size = GB(1);
+		ret = __xe_bo_create_caching(fd, ctx->vm_id, bo->size, placement, 0,
+					     DRM_XE_GEM_CPU_CACHING_WC, &bo->handle);
+		if (ret) {
+			int saved_errno = errno; /* capture before anything can clobber it */
+
+			bind->n_bufs = i;
+			if (saved_errno == ENOMEM || saved_errno == ENOSPC) {
+				/* Continue on OOM, expected when oversubscribing the VM */
+				igt_debug("%s allocation failed at buffer %d (OOM)\n", mem_type, i);
+				break;
+			}
+			/* We are returning as this is a fail scenario */
+			igt_warn("%s allocation failed at buffer %d: %s\n",
+				 mem_type, i, strerror(saved_errno));
+			return -saved_errno;
+		}
+		bo->ptr = NULL;
+		bo->addr = *addr;
+		*addr += bo->size;
+		igt_debug("%s buffer %d created at 0x%016lx\n", mem_type, i, bo->addr);
+	}
+	return 0;
+}
+
+static void cleanup_sram_vram_objs(int fd, struct mem_bind_sync *vram_bind,
+				   struct mem_bind_sync *sram_bind)
+{
+	for (int i = 0; i < vram_bind->n_bufs; i++)
+		gem_close(fd, vram_bind->bufs[i].handle);
+	for (int i = 0; i < sram_bind->n_bufs; i++)
+		gem_close(fd, sram_bind->bufs[i].handle);
+	free(vram_bind->bufs);
+	free(sram_bind->bufs);
+	if (vram_bind->binds_ufence)
+		free(vram_bind->binds_ufence);
+	if (sram_bind->binds_ufence)
+		free(sram_bind->binds_ufence);
+}
+
+static void test_vm_oversubscribe_concurrent_bind(int fd)
+{
+	int n_proc = 0, n_vram_bufs = 0, n_sram_bufs = 0;
+	uint64_t max_by_mem;
+	uint64_t total_vram_demand = 0;
+	uint64_t vram_size = xe_visible_available_vram_size(fd, 0);
+	uint64_t sram_avail = (uint64_t)igt_get_avail_ram_mb() << 20;
+	uint64_t target_vram = vram_size * 2;
+	uint64_t target_sram, total_vram_bufs, total_sram_bufs;
+	struct process_data *pdata;
+
+	/*
+	 * Dynamically cap VRAM oversubscription so the overflow into system
+	 * RAM stays within 25% of available RAM. On small-VRAM platforms
+	 * (e.g. BMG) the 2x target fits within the cap and behavior is
+	 * unchanged; on large-VRAM platforms (e.g. PVC) this prevents OOM.
+	 */
+	target_vram = min(target_vram, vram_size + sram_avail / 4);
+	target_sram = min_t(uint64_t, sram_avail * 50 / 100,
+			    MAX_SRAM_TEST_SIZE);
+
+	total_vram_bufs = target_vram / GB(1);
+	total_sram_bufs = target_sram / GB(1);
+
+	/* determine concurrency from memory pressure */
+
+	max_by_mem = min(total_vram_bufs / MIN_BUFS_PER_PROC,
+			 total_sram_bufs / MIN_BUFS_PER_PROC);
+	n_proc = min_t(int, max_by_mem, MAX_PROCS);
+	igt_require_f(n_proc > 0, "Not enough VRAM/RAM for oversubscription test\n");

+	igt_waitchildren();
+	igt_reset_timeout();
+
+	pthread_cond_destroy(&pdata->cond);
+	pthread_mutex_destroy(&pdata->mutex);
+	igt_assert_eq(munmap(pdata, sizeof(*pdata)), 0);
+}
+
  static void alloc_sizes_init(void)
  {
  	int i;

@@ -984,6 +1476,8 @@ static const struct test_case test_matrix[] = {
  	  false },
  	{ "threads-leak-binding-rand-sizes-50-unaligned", 50,
  	  LEAK_BINDING | UNALIGNED, TYPE_THREAD, false },
+	{ "test_vm_oversubscribe_concurrent_bind", 0, 0,
+	  TYPE_OVERSUBSCRIBE, false},

  };
  
  int igt_main()

@@ -1010,6 +1504,10 @@ int igt_main()
  				run_threaded_bo_alloc_test(fd, t->count, t->flags);
  			}
  			break;
+		case TYPE_OVERSUBSCRIBE:
+			igt_subtest_f("%s", t->name)
+				test_vm_oversubscribe_concurrent_bind(fd);
+			break;
  		case TYPE_ALL_SIZES:
  		case TYPE_SINGLE:
  		case TYPE_ARRAY_BIND: