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Update volume rendering workload: use AVX, remove reduce_equal() path.

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Both of these changes gave a performance benefit!
This commit is contained in:
Matt Pharr
2011-12-09 17:40:50 -08:00
parent d2fa735ef1
commit 0b2febcec0
4 changed files with 24 additions and 63 deletions
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4
docs/perf.txt
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@@ -46,8 +46,8 @@ also included in the ``examples/`` directory.)
- 4.05x
- 15.53x
* - `Volume Rendering`_
- 3.11x
- 15.80x
- 3.60x
- 17.53x
.. _AOBench: https://github.com/ispc/ispc/tree/master/examples/aobench

6
examples/volume_rendering/Makefile
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@@ -8,10 +8,10 @@ TASK_OBJ=$(addprefix objs/, $(subst ../,, $(TASK_CXX:.cpp=.o)))
CXX=g++
CXXFLAGS=-Iobjs/ -O3 -Wall -m64
ISPC=ispc
ISPCFLAGS=-O2 --target=sse2,sse4-x2 --arch=x86-64
ISPCFLAGS=-O2 --target=sse2,sse4-x2,avx --arch=x86-64
OBJS=objs/volume.o objs/volume_serial.o $(TASK_OBJ) objs/volume_ispc.o \
objs/volume_ispc_sse2.o objs/volume_ispc_sse4.o
objs/volume_ispc_sse2.o objs/volume_ispc_sse4.o objs/volume_ispc_avx.o
default: volume
@@ -34,5 +34,5 @@ objs/%.o: ../%.cpp
objs/volume.o: objs/volume_ispc.h
objs/%_ispc.h objs/%_ispc.o objs/%_ispc_sse2.o objs/%_ispc_sse4.o: %.ispc
objs/%_ispc.h objs/%_ispc.o objs/%_ispc_sse2.o objs/%_ispc_sse4.o objs/%_ispc_avx.o: %.ispc
$(ISPC) $(ISPCFLAGS) $< -o objs/$*_ispc.o -h objs/$*_ispc.h

61
examples/volume_rendering/volume.ispc
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@@ -124,24 +124,13 @@ static inline float D(int x, int y, int z, uniform int nVoxels[3],
}
static inline float Du(uniform int x, uniform int y, uniform int z,
uniform int nVoxels[3], uniform float density[]) {
x = clamp(x, 0, nVoxels[0]-1);
y = clamp(y, 0, nVoxels[1]-1);
z = clamp(z, 0, nVoxels[2]-1);
return density[z*nVoxels[0]*nVoxels[1] + y*nVoxels[0] + x];
}
static inline float3 Offset(float3 p, float3 pMin, float3 pMax) {
return (p - pMin) / (pMax - pMin);
}
static inline float Density(float3 Pobj, float3 pMin, float3 pMax,
uniform float density[], uniform int nVoxels[3],
uniform bool &checkForSameVoxel) {
uniform float density[], uniform int nVoxels[3]) {
if (!Inside(Pobj, pMin, pMax))
return 0;
// Compute voxel coordinates and offsets for _Pobj_
@@ -153,39 +142,14 @@ static inline float Density(float3 Pobj, float3 pMin, float3 pMax,
float dx = vox.x - vx, dy = vox.y - vy, dz = vox.z - vz;
// Trilinearly interpolate density values to compute local density
float d00, d10, d01, d11;
uniform int uvx, uvy, uvz;
if (checkForSameVoxel && reduce_equal(vx, &uvx) && reduce_equal(vy, &uvy) &&
reduce_equal(vz, &uvz)) {
// If all of the program instances are inside the same voxel, then
// we'll call the 'uniform' variant of the voxel density lookup
// function, thus doing a single load for each value rather than a
// gather.
d00 = Lerp(dx, Du(uvx, uvy, uvz, nVoxels, density),
Du(uvx+1, uvy, uvz, nVoxels, density));
d10 = Lerp(dx, Du(uvx, uvy+1, uvz, nVoxels, density),
Du(uvx+1, uvy+1, uvz, nVoxels, density));
d01 = Lerp(dx, Du(uvx, uvy, uvz+1, nVoxels, density),
Du(uvx+1, uvy, uvz+1, nVoxels, density));
d11 = Lerp(dx, Du(uvx, uvy+1, uvz+1, nVoxels, density),
Du(uvx+1, uvy+1, uvz+1, nVoxels, density));
}
else {
// Otherwise, we have to do an actual gather in the more general
// D() function. Once the reduce_equal tests above fail, we stop
// checking in subsequent steps, since it's unlikely that this will
// be true in the future once they've diverged into different
// voxels.
checkForSameVoxel = false;
d00 = Lerp(dx, D(vx, vy, vz, nVoxels, density),
D(vx+1, vy, vz, nVoxels, density));
d10 = Lerp(dx, D(vx, vy+1, vz, nVoxels, density),
D(vx+1, vy+1, vz, nVoxels, density));
d01 = Lerp(dx, D(vx, vy, vz+1, nVoxels, density),
D(vx+1, vy, vz+1, nVoxels, density));
d11 = Lerp(dx, D(vx, vy+1, vz+1, nVoxels, density),
D(vx+1, vy+1, vz+1, nVoxels, density));
}
float d00 = Lerp(dx, D(vx, vy, vz, nVoxels, density),
D(vx+1, vy, vz, nVoxels, density));
float d10 = Lerp(dx, D(vx, vy+1, vz, nVoxels, density),
D(vx+1, vy+1, vz, nVoxels, density));
float d01 = Lerp(dx, D(vx, vy, vz+1, nVoxels, density),
D(vx+1, vy, vz+1, nVoxels, density));
float d11 = Lerp(dx, D(vx, vy+1, vz+1, nVoxels, density),
D(vx+1, vy+1, vz+1, nVoxels, density));
float d0 = Lerp(dy, d00, d10);
float d1 = Lerp(dy, d01, d11);
return Lerp(dz, d0, d1);
@@ -221,10 +185,8 @@ transmittance(uniform float3 p0, float3 p1, uniform float3 pMin,
float t = rayT0;
float3 pos = ray.origin + ray.dir * rayT0;
float3 dirStep = ray.dir * stepT;
uniform bool checkForSameVoxel = true;
while (t < rayT1) {
tau += stepDist * sigma_t * Density(pos, pMin, pMax, density, nVoxels,
checkForSameVoxel);
tau += stepDist * sigma_t * Density(pos, pMin, pMax, density, nVoxels);
pos = pos + dirStep;
t += stepT;
}
@@ -268,9 +230,8 @@ raymarch(uniform float density[], uniform int nVoxels[3], Ray ray) {
float t = rayT0;
float3 pos = ray.origin + ray.dir * rayT0;
float3 dirStep = ray.dir * stepT;
uniform bool checkForSameVoxel = true;
cwhile (t < rayT1) {
float d = Density(pos, pMin, pMax, density, nVoxels, checkForSameVoxel);
float d = Density(pos, pMin, pMax, density, nVoxels);
// terminate once attenuation is high
float atten = exp(-tau);

16
examples/volume_rendering/volume.vcxproj
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@@ -156,18 +156,18 @@
<ItemGroup>
<CustomBuild Include="volume.ispc">
<FileType>Document</FileType>
<Command Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --arch=x86 --target=sse2,sse4-x2
<Command Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --arch=x86 --target=sse2,sse4-x2,avx
</Command>
<Command Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --target=sse2,sse4-x2
<Command Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --target=sse2,sse4-x2,avx
</Command>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Command Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --arch=x86 --target=sse2,sse4-x2
<Outputs Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_avx.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_avx.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Command Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --arch=x86 --target=sse2,sse4-x2,avx
</Command>
<Command Condition="'$(Configuration)|$(Platform)'=='Release|x64'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --target=sse2,sse4-x2
<Command Condition="'$(Configuration)|$(Platform)'=='Release|x64'">ispc -O2 %(Filename).ispc -o $(TargetDir)%(Filename).obj -h $(TargetDir)%(Filename)_ispc.h --target=sse2,sse4-x2,avx
</Command>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Release|x64'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_avx.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
<Outputs Condition="'$(Configuration)|$(Platform)'=='Release|x64'">$(TargetDir)%(Filename).obj;$(TargetDir)%(Filename)_sse2.obj;$(TargetDir)%(Filename)_sse4.obj;$(TargetDir)%(Filename)_avx.obj;$(TargetDir)%(Filename)_ispc.h</Outputs>
</CustomBuild>
</ItemGroup>
<Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />