The current algorithm requires threads to commit/cancel waiting in order
they called Prewait. Spinning caused by that serialization can consume
lots of CPU time on some workloads. Restructure the algorithm to not
require that serialization and remove spin waits from Commit/CancelWait.
Note: this reduces max number of threads from 2^16 to 2^14 to leave
more space for ABA counter (which is now 22 bits).
Implementation details are explained in comments.
- cleanup noise in imaginary part of real roots
- take into account the magnitude of the derivative to check roots.
- use <= instead of < at appropriate places
evalShardedByInnerDim ensures that the values it passes for start_k and
end_k to evalGemmPartialWithoutOutputKernel are multiples of 8 as the kernel
does not work correctly when the values of k are not multiples of the
packet_size. While this precaution works for AVX builds, it is insufficient
for AVX512 builds where the maximum packet size is 16. The result is slightly
incorrect float32 contractions on AVX512 builds.
This commit fixes the problem by ensuring that k is always a multiple of
the packet_size if the packet_size is > 8.
Add parallel memcpy to TensorThreadPoolDevice in Eigen, but limit the number of threads to 4, beyond which we just seem to be wasting CPU cycles as the threads contend for memory bandwidth.
Approved-by: Eugene Zhulenev <ezhulenev@google.com>
- unsupported/Eigen/CXX11/src/Tensor/TensorReductionGpu.h
Changing "pass-by-reference" argument to be "pass-by-value" instead
(in a __global__ function decl).
"pass-by-reference" arguments to __global__ functions are unwise,
and will be explicitly flagged as errors by the newer versions of HIP.
- Eigen/src/Core/util/Memory.h
- unsupported/Eigen/CXX11/src/Tensor/TensorContraction.h
Changes introduced in recent commits breaks the HIP compile.
Adding EIGEN_DEVICE_FUNC attribute to some functions and
calling ::malloc/free instead of the corresponding std:: versions
to get the HIP compile working again
- unsupported/Eigen/CXX11/src/Tensor/TensorReduction.h
Change introduced a recent commit breaks the HIP compile
(link stage errors out due to failure to inline a function).
Disabling the recently introduced code (only for HIP compile), to get
the eigen nightly testing going again.
Will submit another PR once we have te proper fix.
- Eigen/src/Core/util/ConfigureVectorization.h
Enabling GPU VECTOR support when HIP compiler is in use
(for both the host and device compile phases)
