Pipeline statistics queries allow the application to sample a specified set
of VkPipeline
counters. These counters are accumulated by Vulkan
for a set of either draw or dispatch commands while a pipeline statistics
query is active. As such, pipeline statistics queries are available on
queue families supporting either graphics or compute operations. Further,
the availability of pipeline statistics queries is indicated by the
pipelineStatisticsQuery
member of the VkPhysicalDeviceFeatures
object (see vkGetPhysicalDeviceFeatures
and vkCreateDevice
for
detecting and requesting this query type on a VkDevice
).
A pipeline statistics query is begun and ended by calling
vkCmdBeginQuery
and vkCmdEndQuery
, respectively. When a pipeline
statistics query begins, all statistics counters are set to zero. While the
query is active, the pipeline type determines which set of statistics are
available, but these must be configured on the query pool when it is
created. If a statistic counter is issued on a command buffer that does
not support the corresponding operation, that counter is
undefined after the query has finished. At least one statistic counter
relevant to the operations supported on the recording command buffer
must be enabled.
The pipeline statistic counters are individually enabled for query pools with
VkQueryPoolCreateInfo
::pipelineStatistics
, and for secondary command
buffers with VkCommandBufferInheritanceInfo
::pipelineStatistics
.
Bits which can be set in pipelineStatistics
include:
typedef enum VkQueryPipelineStatisticFlagBits { VK_QUERY_PIPELINE_STATISTIC_INPUT_ASSEMBLY_VERTICES_BIT = 0x00000001, VK_QUERY_PIPELINE_STATISTIC_INPUT_ASSEMBLY_PRIMITIVES_BIT = 0x00000002, VK_QUERY_PIPELINE_STATISTIC_VERTEX_SHADER_INVOCATIONS_BIT = 0x00000004, VK_QUERY_PIPELINE_STATISTIC_GEOMETRY_SHADER_INVOCATIONS_BIT = 0x00000008, VK_QUERY_PIPELINE_STATISTIC_GEOMETRY_SHADER_PRIMITIVES_BIT = 0x00000010, VK_QUERY_PIPELINE_STATISTIC_CLIPPING_INVOCATIONS_BIT = 0x00000020, VK_QUERY_PIPELINE_STATISTIC_CLIPPING_PRIMITIVES_BIT = 0x00000040, VK_QUERY_PIPELINE_STATISTIC_FRAGMENT_SHADER_INVOCATIONS_BIT = 0x00000080, VK_QUERY_PIPELINE_STATISTIC_TESSELLATION_CONTROL_SHADER_PATCHES_BIT = 0x00000100, VK_QUERY_PIPELINE_STATISTIC_TESSELLATION_EVALUATION_SHADER_INVOCATIONS_BIT = 0x00000200, VK_QUERY_PIPELINE_STATISTIC_COMPUTE_SHADER_INVOCATIONS_BIT = 0x00000400, } VkQueryPipelineStatisticFlagBits;
These bits have the following meanings:
VK_QUERY_PIPELINE_STATISTIC_INPUT_ASSEMBLY_VERTICES_BIT
is set,
queries managed by the pool will count the number of vertices processed
by the input assembly stage. Vertices corresponding to
incomplete primitives may contribute to the count.
VK_QUERY_PIPELINE_STATISTIC_INPUT_ASSEMBLY_PRIMITIVES_BIT
is
set, queries managed by the pool will count the number of primitives
processed by the input assembly stage. If primitive restart
is enabled, restarting the primitive topology has no effect on the
count. Incomplete primitives may be counted.
VK_QUERY_PIPELINE_STATISTIC_VERTEX_SHADER_INVOCATIONS_BIT
is
set, queries managed by the pool will count the number of vertex shader
invocations. This counter’s value is incremented each time a vertex
shader is invoked.
VK_QUERY_PIPELINE_STATISTIC_GEOMETRY_SHADER_INVOCATIONS_BIT
is
set, queries managed by the pool will count the number of geometry
shader invocations. This counter’s value is incremented each time a
geometry shader is invoked. In the case
of instanced geometry shaders, the geometry
shader invocations count is incremented for each separate instanced
invocation.
VK_QUERY_PIPELINE_STATISTIC_GEOMETRY_SHADER_PRIMITIVES_BIT
is
set, queries managed by the pool will count the number of primitives
generated by geometry shader invocations. The counter’s value is
incremented each time the geometry shader emits a primitive. Restarting
primitive topology using the SPIR-V instructions OpEndPrimitive
or
OpEndStreamPrimitive
has no effect on the geometry shader output
primitives count.
VK_QUERY_PIPELINE_STATISTIC_CLIPPING_INVOCATIONS_BIT
is set,
queries managed by the pool will count the number of primitives
processed by the Primitive Clipping stage of
the pipeline. The counter’s value is incremented each time a primitive
reaches the primitive clipping stage.
If VK_QUERY_PIPELINE_STATISTIC_CLIPPING_PRIMITIVES_BIT
is set,
queries managed by the pool will count the number of primitives output
by the Primitive Clipping stage of the
pipeline. The counter’s value is incremented each time a primitive
passes the primitive clipping stage. The actual number of primitives
output by the primitive clipping stage for a particular input primitive
is implementation-dependent but must satisfy the following conditions:
VK_QUERY_PIPELINE_STATISTIC_FRAGMENT_SHADER_INVOCATIONS_BIT
is
set, queries managed by the pool will count the number of fragment
shader invocations. The counter’s value is incremented each time the
fragment shader is invoked.
VK_QUERY_PIPELINE_STATISTIC_TESSELLATION_CONTROL_SHADER_PATCHES_BIT
is set, queries managed by the pool will count the number of patches
processed by the tessellation control shader. The counter’s value is
incremented once for each patch for which a tessellation control shader
is invoked.
VK_QUERY_PIPELINE_STATISTIC_TESSELLATION_EVALUATION_SHADER_INVOCATIONS_BIT
is set, queries managed by the pool will count the number of invocations
of the tessellation evaluation shader. The counter’s value is
incremented each time the tessellation evaluation shader is
invoked.
VK_QUERY_PIPELINE_STATISTIC_COMPUTE_SHADER_INVOCATIONS_BIT
is
set, queries managed by the pool will count the number of compute shader
invocations. The counter’s value is incremented every time the compute
shader is invoked. Implementations may skip the execution of certain
compute shader invocations or execute additional compute shader
invocations for implementation-dependent reasons as long as the results
of rendering otherwise remain unchanged.
These values are intended to measure relative statistics on one implementation. Various device architectures will count these values differently. Any or all counters may be affected by the issues described in Query Operation.
![]() | Note |
---|---|
For example, tile-based rendering devices may need to replay the scene multiple times, affecting some of the counts. |
If a pipeline has rasterizerDiscardEnable
enabled, implementations
may discard primitives after the final vertex processing stage. As a
result, if rasterizerDiscardEnable
is enabled, the clipping input and
output primitives counters may not be incremented.
When a pipeline statistics query finishes, the result for that query is
marked as available. The application can copy the result to a
buffer (via vkCmdCopyQueryPoolResults
), or request it be put into host
memory (via vkGetQueryPoolResults
).