For selftests, we desire repeatability and so prefer using a prng with
known seed over true randomness. Extract random_offset() as a selftest
utility that can take the prng state.
Suggested-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
---
drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 14 ++++++++-----
drivers/gpu/drm/i915/selftests/i915_random.c | 20 +++++++++++++++++++
drivers/gpu/drm/i915/selftests/i915_random.h | 4 ++++
3 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 0d40e0b42923..b6fce404aacb 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -1299,6 +1299,7 @@ static int igt_gtt_reserve(void *arg)
{
struct i915_ggtt *ggtt = arg;
struct drm_i915_gem_object *obj, *on;
+ I915_RND_STATE(prng);
LIST_HEAD(objects);
u64 total;
int err = -ENODEV;
@@ -1425,9 +1426,10 @@ static int igt_gtt_reserve(void *arg)
goto out;
}
- offset = random_offset(0, ggtt->vm.total,
- 2*I915_GTT_PAGE_SIZE,
- I915_GTT_MIN_ALIGNMENT);
+ offset = igt_random_offset(&prng,
+ 0, ggtt->vm.total,
+ 2*I915_GTT_PAGE_SIZE,
+ I915_GTT_MIN_ALIGNMENT);
err = i915_gem_gtt_reserve(&ggtt->vm, &vma->node,
obj->base.size,
@@ -1772,6 +1774,7 @@ static int igt_cs_tlb(void *arg)
struct intel_context *ce;
struct drm_file *file;
struct i915_vma *vma;
+ I915_RND_STATE(prng);
unsigned int i;
u32 *result;
u32 *batch;
@@ -1885,8 +1888,9 @@ static int igt_cs_tlb(void *arg)
struct i915_request *rq;
u64 offset;
- offset = random_offset(0, vm->total - PAGE_SIZE,
- chunk_size, PAGE_SIZE);
+ offset = igt_random_offset(&prng,
+ 0, vm->total - PAGE_SIZE,
+ chunk_size, PAGE_SIZE);
err = vm->allocate_va_range(vm, offset, chunk_size);
if (err)
diff --git a/drivers/gpu/drm/i915/selftests/i915_random.c b/drivers/gpu/drm/i915/selftests/i915_random.c
index 716a3f19f030..abdfadcf626b 100644
--- a/drivers/gpu/drm/i915/selftests/i915_random.c
+++ b/drivers/gpu/drm/i915/selftests/i915_random.c
@@ -29,6 +29,7 @@
#include <linux/types.h>
#include "i915_random.h"
+#include "i915_utils.h"
u64 i915_prandom_u64_state(struct rnd_state *rnd)
{
@@ -87,3 +88,22 @@ unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
i915_random_reorder(order, count, state);
return order;
}
+
+u64 igt_random_offset(struct rnd_state *state,
+ u64 start, u64 end,
+ u64 len, u64 align)
+{
+ u64 range, addr;
+
+ BUG_ON(range_overflows(start, len, end));
+ BUG_ON(round_up(start, align) > round_down(end - len, align));
+
+ range = round_down(end - len, align) - round_up(start, align);
+ if (range) {
+ addr = i915_prandom_u64_state(state);
+ div64_u64_rem(addr, range, &addr);
+ start += addr;
+ }
+
+ return round_up(start, align);
+}
diff --git a/drivers/gpu/drm/i915/selftests/i915_random.h b/drivers/gpu/drm/i915/selftests/i915_random.h
index 8e1ff9c105b6..35cc69a3a1b9 100644
--- a/drivers/gpu/drm/i915/selftests/i915_random.h
+++ b/drivers/gpu/drm/i915/selftests/i915_random.h
@@ -57,4 +57,8 @@ void i915_random_reorder(unsigned int *order,
void i915_prandom_shuffle(void *arr, size_t elsz, size_t count,
struct rnd_state *state);
+u64 igt_random_offset(struct rnd_state *state,
+ u64 start, u64 end,
+ u64 len, u64 align);
+
#endif /* !__I915_SELFTESTS_RANDOM_H__ */
--
2.23.0
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