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77 lines
3.5 KiB
77 lines
3.5 KiB
4 months ago
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drawElements Quality Program Test Specification
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-----------------------------------------------
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Copyright 2014 The Android Open Source Project
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-------------------------------------------------------------------------
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Shader operator performance tests
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Tests:
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+ dEQP-GLES3.performance.shaders.operator.*
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Includes:
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+ Arithmetic operators in vertex and fragment shaders
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- Scalar and vector types
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+ Computation-only built-in functions
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Excludes:
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+ Texture lookup built-in functions
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- Covered in performance.texture.
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+ Certain built-in functions; to be added in the future
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- modf
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- functions with uint/uvec* return or parameter types
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- matrix functions that also deal with non-matrices (e.g. outerProduct)
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Description:
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Each test case draws multiple times with different workload sizes. A workload
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size means the iteration count of a uniform loop in the shader. Time for each
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frame is measured, and the slope of the workload size vs frame time data is
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estimated. This slope tells us the estimated increase in frame time caused by
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a workload increase of 1 loop iteration.
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Generally, the shaders contain not just the operation we're interested in (e.g.
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addition) but also some other things (e.g. loop overhead). To eliminate this
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cost, we actually do the measurements described above paragraph with two
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programs, which contain different amounts of computation in the loop. Then we
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can compute the cost of just one operation by appropriately subtracting the
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estimated slopes, and dividing by the operation count difference between the
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two programs.
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At this point, the result tells us the increase in frame time caused by the
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addition of one operation. Dividing this by the amount of draw calls in a frame,
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and further by the amount of vertices or fragments in a draw call, we get the
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time cost of one operation.
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In reality, there sometimes isn't just a trivial linear dependence between
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workload size and frame time. Instead, there tends to be some amount of initial
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"free" operations. That is, it may be that all workload sizes below some number
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C yield the same frame time, and only workload sizes beyond C increase the frame
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time in a supposedly linear manner. Graphically, this means that there graph
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consists of two parts: a horizontal left part, and a linearly increasing right
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part; the right part starts where the left parts ends. The principal task of
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these tests is to look at the slope of the increasing right part. Additionally
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an estimate for the amount of initial free operations is calculated. Note that
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it is also normal to get graphs where the horizontal left part is of zero width,
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i.e. there are no free operations.
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Note that the tests use several fixed constants, such as the extent to which the
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loops in the shaders are unrolled. These may not be the most suitable for all
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platforms, and can be modified near the top of es2pShaderOperatorTests.cpp .
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The unit of the test result is millions of operations per second.
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See performance.txt for more details on shader performance testing.
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