Because WAIT_REG_MEM can only wait for a 32-bit value, it's not
safe to use it for timestamp queries. If we only wait on the low
32 bits of a timestamp query we could be unlucky and the GPU
might hang.

One possible fix is to emit a full end of pipe event and wait
on a 32-bit value which is actually an availability bit. This
bit is allocated at creation time and always cleared before
emitting the EOP event.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108925
Fixes: 5d6a560a29 ("radv: do not use the availability bit for timestamp 
queries")
Signed-off-by: Samuel Pitoiset <[email protected]>
---
 src/amd/vulkan/radv_query.c | 49 +++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/src/amd/vulkan/radv_query.c b/src/amd/vulkan/radv_query.c
index 550abe307a1..9bb6b660add 100644
--- a/src/amd/vulkan/radv_query.c
+++ b/src/amd/vulkan/radv_query.c
@@ -1056,8 +1056,15 @@ VkResult radv_CreateQueryPool(
        pool->pipeline_stats_mask = pCreateInfo->pipelineStatistics;
        pool->availability_offset = pool->stride * pCreateInfo->queryCount;
        pool->size = pool->availability_offset;
-       if (pCreateInfo->queryType == VK_QUERY_TYPE_PIPELINE_STATISTICS)
+       if (pCreateInfo->queryType == VK_QUERY_TYPE_PIPELINE_STATISTICS) {
                pool->size += 4 * pCreateInfo->queryCount;
+       } else if (pCreateInfo->queryType == VK_QUERY_TYPE_TIMESTAMP) {
+               /* Allocate one DWORD for the availability bit which is needed
+                * for vkCmdCopyQueryPoolResults() because we can't perform a
+                * WAIT_REG_MEM on a 64-bit value.
+                */
+               pool->size += 4;
+       }
 
        pool->bo = device->ws->buffer_create(device->ws, pool->size,
                                             64, RADEON_DOMAIN_GTT, 
RADEON_FLAG_NO_INTERPROCESS_SHARING);
@@ -1328,19 +1335,45 @@ void radv_CmdCopyQueryPoolResults(
                                  pool->availability_offset + 4 * firstQuery);
                break;
        case VK_QUERY_TYPE_TIMESTAMP:
+               if (flags & VK_QUERY_RESULT_WAIT_BIT) {
+                       /* Emit a full end of pipe event because we can't
+                        * perform a WAIT_REG_MEM on a 64-bit value. If we only
+                        * do a WAIT_REG_MEM on the low 32 bits of a timestamp
+                        * query we could be unlucky and the GPU might hang.
+                        */
+                       enum chip_class chip = 
cmd_buffer->device->physical_device->rad_info.chip_class;
+                       bool is_mec = radv_cmd_buffer_uses_mec(cmd_buffer);
+                       uint64_t avail_va = va + pool->availability_offset;
+
+                       /* Clear the availability bit before waiting on the end
+                        * of pipe event.
+                        */
+                       radeon_emit(cs, PKT3(PKT3_WRITE_DATA, 3, 0));
+                       radeon_emit(cs, S_370_DST_SEL(V_370_MEM_ASYNC) |
+                                       S_370_WR_CONFIRM(1) |
+                                       S_370_ENGINE_SEL(V_370_ME));
+                       radeon_emit(cs, avail_va);
+                       radeon_emit(cs, avail_va >> 32);
+                       radeon_emit(cs, 0xdeadbeef);
+
+                       /* Wait for all prior GPU work. */
+                       si_cs_emit_write_event_eop(cs, chip, is_mec,
+                                                  V_028A90_BOTTOM_OF_PIPE_TS, 
0,
+                                                  EOP_DATA_SEL_VALUE_32BIT,
+                                                  avail_va, 0, 1,
+                                                  cmd_buffer->gfx9_eop_bug_va);
+
+                       /* Wait on the timestamp value. */
+                       radv_cp_wait_mem(cs, WAIT_REG_MEM_EQUAL, avail_va,
+                                        1, 0xffffffff);
+               }
+
                for(unsigned i = 0; i < queryCount; ++i, dest_va += stride) {
                        unsigned query = firstQuery + i;
                        uint64_t local_src_va = va  + query * pool->stride;
 
                        MAYBE_UNUSED unsigned cdw_max = 
radeon_check_space(cmd_buffer->device->ws, cs, 19);
 
-
-                       if (flags & VK_QUERY_RESULT_WAIT_BIT) {
-                               radv_cp_wait_mem(cs, WAIT_REG_MEM_NOT_EQUAL,
-                                                local_src_va,
-                                                TIMESTAMP_NOT_READY >> 32,
-                                                0xffffffff);
-                       }
                        if (flags & VK_QUERY_RESULT_WITH_AVAILABILITY_BIT) {
                                uint64_t avail_dest_va = dest_va + elem_size;
 
-- 
2.19.2

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