drm/i915/selftests: Extract random_offset() for use with a prng

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@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191002122430.23205-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 0d40e0b429230dda68a501ddf9afd82c7871683d..f901bbb9586e02610cd074bcd8826986f1c8a7ba 100644 (file)
--- 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 716a3f19f03035fe2cf6fd4c126ea8ca14092d8f..abdfadcf626bdfd1ef612504166751f19053c76e 100644 (file)
--- 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 8e1ff9c105b66a1ad74f99f08cdae9544987bfa8..35cc69a3a1b99abcb7e7fa181bac46abec8fcd74 100644 (file)
--- 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__ */