[igt-dev] [PATCH i-g-t] lib/intel_memory_region: Use separate context for probing offset and alignment
Matthew Auld
matthew.auld at intel.com
Mon May 9 11:43:11 UTC 2022
On 09/05/2022 12:30, Zbigniew Kempczyński wrote:
> Probing alignment/offset (A/O) in default context works properly only
> when there're no processes which competes on same vm space. To avoid
> risk that single probe will be called on already used offset in another
> process lets use dedicated context for this purpose if possible.
>
> In other words when forking occur without A/O cache filled (subject of
> COW) children will exercise A/O individually. Using same default context
> leads to risk of probing offset which is in flight in another child
> thus we can get different A/O. Such behavior is not allowed as allocator
> infrastructure requires same type, strategy and alignment on single vm.
> We expect coherent A/O in different children so we try to use separate
> context to fill this requirement.
>
> v2: on old gens where're no logical contexts use default context
>
> Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/5729
> ---
> lib/i915/intel_memory_region.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/lib/i915/intel_memory_region.c b/lib/i915/intel_memory_region.c
> index 593f4bedc8..c0f67bd737 100644
> --- a/lib/i915/intel_memory_region.c
> +++ b/lib/i915/intel_memory_region.c
> @@ -630,7 +630,7 @@ uint64_t gem_detect_min_start_offset_for_region(int i915, uint32_t region)
> struct drm_i915_gem_execbuffer2 eb;
> uint64_t start_offset = 0;
> uint64_t bb_size = PAGE_SIZE;
> - uint32_t *batch;
> + uint32_t *batch, ctx = 0;
> uint16_t devid = intel_get_drm_devid(i915);
> struct cache_entry *entry, *newentry;
>
> @@ -640,12 +640,16 @@ uint64_t gem_detect_min_start_offset_for_region(int i915, uint32_t region)
> goto out;
> pthread_mutex_unlock(&cache_mutex);
>
> + /* Use separate context if possible to avoid offset overlapping */
> + __gem_context_create(i915, &ctx);
> +
> memset(&obj, 0, sizeof(obj));
> memset(&eb, 0, sizeof(eb));
>
> eb.buffers_ptr = to_user_pointer(&obj);
> eb.buffer_count = 1;
> eb.flags = I915_EXEC_DEFAULT;
> + eb.rsvd1 = ctx;
> igt_assert(__gem_create_in_memory_regions(i915, &obj.handle, &bb_size, region) == 0);
> obj.flags = EXEC_OBJECT_PINNED;
>
> @@ -670,6 +674,7 @@ uint64_t gem_detect_min_start_offset_for_region(int i915, uint32_t region)
> igt_assert(start_offset <= 1ull << 48);
> }
> gem_close(i915, obj.handle);
> + gem_context_destroy(i915, ctx);
if (ctx)
gem_context_destroy();
?
r-b still stands, assuming CI is now happy :)
>
> newentry = malloc(sizeof(*newentry));
> if (!newentry)
> @@ -770,7 +775,7 @@ uint64_t gem_detect_min_alignment_for_regions(int i915,
> struct drm_i915_gem_execbuffer2 eb;
> uint64_t min_alignment = PAGE_SIZE;
> uint64_t bb_size = PAGE_SIZE, obj_size = PAGE_SIZE;
> - uint32_t *batch;
> + uint32_t *batch, ctx = 0;
> uint16_t devid = intel_get_drm_devid(i915);
> struct cache_entry *entry, *newentry;
>
> @@ -780,6 +785,9 @@ uint64_t gem_detect_min_alignment_for_regions(int i915,
> goto out;
> pthread_mutex_unlock(&cache_mutex);
>
> + /* Use separate context if possible to avoid offset overlapping */
> + __gem_context_create(i915, &ctx);
> +
> memset(obj, 0, sizeof(obj));
> memset(&eb, 0, sizeof(eb));
>
> @@ -787,6 +795,7 @@ uint64_t gem_detect_min_alignment_for_regions(int i915,
> eb.buffers_ptr = to_user_pointer(obj);
> eb.buffer_count = ARRAY_SIZE(obj);
> eb.flags = I915_EXEC_BATCH_FIRST | I915_EXEC_DEFAULT;
> + eb.rsvd1 = ctx;
> igt_assert(__gem_create_in_memory_regions(i915, &obj[0].handle,
> &bb_size, region1) == 0);
>
> @@ -815,6 +824,8 @@ uint64_t gem_detect_min_alignment_for_regions(int i915,
>
> gem_close(i915, obj[0].handle);
> gem_close(i915, obj[1].handle);
> + if (ctx)
> + gem_context_destroy(i915, ctx);
>
> newentry = malloc(sizeof(*newentry));
> if (!newentry)
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