[igt-dev] [PATCH i-g-t 07/35] lib/intel_allocator_random: Add random allocator

[Zbigniew Kempczyński]

Sometimes we want to experiment with addresses so randomizing can help
us a little.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Dominik Grzegorzek <dominik.grzegorzek at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 lib/intel_allocator_random.c | 204 +++++++++++++++++++++++++++++++++++
 1 file changed, 204 insertions(+)
 create mode 100644 lib/intel_allocator_random.c

diff --git a/lib/intel_allocator_random.c b/lib/intel_allocator_random.c
new file mode 100644
index 000000000..15b930af1
--- /dev/null
+++ b/lib/intel_allocator_random.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <sys/ioctl.h>
+#include <stdlib.h>
+#include "igt.h"
+#include "igt_x86.h"
+#include "igt_rand.h"
+#include "intel_allocator.h"
+
+struct intel_allocator *intel_allocator_random_create(int fd, uint32_t ctx);
+
+struct intel_allocator_random {
+	uint64_t bias;
+	uint32_t prng;
+	uint64_t gtt_size;
+	uint64_t start;
+	uint64_t end;
+
+	/* statistics */
+	uint64_t allocated_objects;
+};
+
+#define GEN8_HIGH_ADDRESS_BIT 47
+static uint64_t gen8_canonical_addr(uint64_t address)
+{
+	int shift = 63 - GEN8_HIGH_ADDRESS_BIT;
+
+	return (int64_t)(address << shift) >> shift;
+}
+
+static uint64_t get_bias(int fd)
+{
+	(void) fd;
+
+	return 256 << 10;
+}
+
+static void intel_allocator_random_get_address_range(struct intel_allocator *ial,
+						     uint64_t *startp,
+						     uint64_t *endp)
+{
+	struct intel_allocator_random *ialr = ial->priv;
+
+	if (startp)
+		*startp = ialr->start;
+
+	if (endp)
+		*endp = ialr->end;
+}
+
+static uint64_t intel_allocator_random_alloc(struct intel_allocator *ial,
+					     uint32_t handle, uint64_t size,
+					     uint64_t alignment)
+{
+	struct intel_allocator_random *ialr = ial->priv;
+	uint64_t offset;
+
+	(void) handle;
+
+	/* randomize the address, we try to avoid relocations */
+	offset = hars_petruska_f54_1_random64(&ialr->prng);
+	offset += ialr->bias; /* Keep the low 256k clear, for negative deltas */
+	offset &= ialr->gtt_size - 1;
+	offset &= ~(alignment - 1);
+	offset = gen8_canonical_addr(offset);
+
+	ialr->allocated_objects++;
+
+	return offset;
+}
+
+static bool intel_allocator_random_free(struct intel_allocator *ial,
+					uint32_t handle)
+{
+	struct intel_allocator_random *ialr = ial->priv;
+
+	(void) handle;
+
+	ialr->allocated_objects--;
+
+	return false;
+}
+
+static bool intel_allocator_random_is_allocated(struct intel_allocator *ial,
+						uint32_t handle, uint64_t size,
+						uint64_t offset)
+{
+	(void) ial;
+	(void) handle;
+	(void) size;
+	(void) offset;
+
+	return false;
+}
+
+static void intel_allocator_random_destroy(struct intel_allocator *ial)
+{
+	igt_assert(ial);
+
+	free(ial->priv);
+	free(ial);
+}
+
+static bool intel_allocator_random_reserve(struct intel_allocator *ial,
+					   uint32_t handle,
+					   uint64_t start, uint64_t end)
+{
+	(void) ial;
+	(void) handle;
+	(void) start;
+	(void) end;
+
+	return false;
+}
+
+static bool intel_allocator_random_unreserve(struct intel_allocator *ial,
+					     uint32_t handle,
+					     uint64_t start, uint64_t end)
+{
+	(void) ial;
+	(void) handle;
+	(void) start;
+	(void) end;
+
+	return false;
+}
+
+static bool intel_allocator_random_is_reserved(struct intel_allocator *ial,
+					       uint64_t start, uint64_t end)
+{
+	(void) ial;
+	(void) start;
+	(void) end;
+
+	return false;
+}
+
+static void intel_allocator_random_print(struct intel_allocator *ial, bool full)
+{
+	struct intel_allocator_random *ialr = ial->priv;
+
+	(void) full;
+
+	igt_info("<fd: %d, ctx: %u> allocated objects: %" PRIx64 "\n",
+		 ial->fd, ial->ctx, ialr->allocated_objects);
+}
+
+static bool intel_allocator_random_is_empty(struct intel_allocator *ial)
+{
+	struct intel_allocator_random *ialr = ial->priv;
+
+	return !ialr->allocated_objects;
+}
+
+struct intel_allocator *intel_allocator_random_create(int fd, uint32_t ctx)
+{
+	struct intel_allocator *ial;
+	struct intel_allocator_random *ialr;
+
+	igt_debug("Using random allocator\n");
+	ial = calloc(1, sizeof(*ial));
+	igt_assert(ial);
+
+	ial->fd = fd;
+	ial->ctx = ctx;
+	ial->get_address_range = intel_allocator_random_get_address_range;
+	ial->alloc = intel_allocator_random_alloc;
+	ial->free = intel_allocator_random_free;
+	ial->is_allocated = intel_allocator_random_is_allocated;
+	ial->reserve = intel_allocator_random_reserve;
+	ial->unreserve = intel_allocator_random_unreserve;
+	ial->is_reserved = intel_allocator_random_is_reserved;
+	ial->destroy = intel_allocator_random_destroy;
+	ial->print = intel_allocator_random_print;
+	ial->is_empty = intel_allocator_random_is_empty;
+
+	ialr = ial->priv = calloc(1, sizeof(*ialr));
+	igt_assert(ial->priv);
+	ialr->prng = (uint32_t) to_user_pointer(ial);
+	ialr->gtt_size = gem_aperture_size(fd);
+	igt_debug("Gtt size: %" PRId64 "\n", ialr->gtt_size);
+	if (!gem_uses_full_ppgtt(fd))
+		ialr->gtt_size /= 2;
+
+	if ((ialr->gtt_size - 1) >> 32) {
+		/*
+		 * We're not aware of bo sizes, so limiting to 46 bit make us
+		 * sure we won't enter to addresses with 47-bit set
+		 * (we use 32-bit size now so still we fit 47-bit address space).
+		 */
+		if (ialr->gtt_size & (3ull << 47))
+			ialr->gtt_size = (1ull << 46);
+	}
+	ialr->bias = get_bias(fd);
+	ialr->start = ialr->bias;
+	ialr->end = ialr->gtt_size;
+
+	ialr->allocated_objects = 0;
+
+	return ial;
+}
-- 
2.26.0