Leverage libxsmm kernels within signle threaded contractions

This commit is contained in:
Benoit Steiner 2016-12-21 12:32:06 -08:00
parent c19fe5e9ed
commit f9eff17e91
3 changed files with 427 additions and 2 deletions

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@ -71,6 +71,10 @@ typedef unsigned __int64 uint64_t;
#include <time.h>
#endif
#if defined(EIGEN_USE_LIBXSMM)
#include "libxsmm.h"
#endif
#ifdef EIGEN_USE_THREADS
#include "ThreadPool"
#endif

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@ -20,6 +20,70 @@ namespace Eigen {
*
*/
namespace internal {
#if defined(EIGEN_VECTORIZE_AVX) && defined(EIGEN_USE_LIBXSMM)
template<typename Scalar, typename Index>
void pack_simple(Scalar * dst, const Scalar * src, Index cols, Index rows, Index lddst, Index ldsrc) {
size_t psize = packet_traits<Scalar>::size; // Packet size
typedef typename packet_traits<Scalar>::type Packet; // Packet type
size_t alignment = psize*sizeof(Scalar); // Needed alignment
if (rows % psize == 0 && (lddst*sizeof(Scalar)) % alignment == 0 &&
(ldsrc*sizeof(Scalar)) % alignment == 0 &&
reinterpret_cast<uintptr_t>(src) % alignment == 0 &&
reinterpret_cast<uintptr_t>(dst) % alignment == 0) {
// Optimized version using packets
size_t num_packets = rows / psize;
for (Index col = 0; col < cols; ++col) {
EIGEN_ASM_COMMENT("begin pack_simple inner copy");
// Unrolled manually 4 times.
for (size_t i=0; i < num_packets/4; ++i) {
internal::pstore(dst, internal::pload<Packet>(src));
dst += psize; src += psize;
internal::pstore(dst, internal::pload<Packet>(src));
dst += psize; src += psize;
internal::pstore(dst, internal::pload<Packet>(src));
dst += psize; src += psize;
internal::pstore(dst, internal::pload<Packet>(src));
dst += psize; src += psize;
}
for (size_t i=0; i < num_packets%4; ++i) {
internal::pstore(dst, internal::pload<Packet>(src));
dst += psize; src += psize;
}
dst += lddst - num_packets*psize;
src += ldsrc - num_packets*psize;
EIGEN_ASM_COMMENT("end pack_simple inner copy");
}
} else {
// Naive memcpy calls
for (Index col = 0; col < cols; ++col) {
memcpy(dst + col*lddst, src + col*ldsrc, rows*sizeof(Scalar));
}
}
}
template<typename LhsScalar, typename RhsScalar, typename Scalar>
struct libxsmm_wrapper {
libxsmm_wrapper() {}
libxsmm_wrapper(int flags, int m, int n, int k, int lda, int ldb, int ldc, float alpha, float beta, int prefetch) {}
void operator()(const LhsScalar* a, const RhsScalar* b, Scalar* c) {}
void operator()(const LhsScalar* a, const RhsScalar* b, Scalar* c, const LhsScalar* ap, const RhsScalar* bp, const Scalar* cp) {}
};
template<>
struct libxsmm_wrapper<float, float, float>: public libxsmm_mmfunction<float> {
libxsmm_wrapper(): libxsmm_mmfunction() {}
libxsmm_wrapper(int flags, int m, int n, int k, int lda, int ldb, int ldc, float alpha, float beta, int prefetch) :
libxsmm_mmfunction(flags, m, n, k, lda, ldb, ldc, alpha, beta, prefetch) {}
};
template<>
struct libxsmm_wrapper<double, double, double>: public libxsmm_mmfunction<double> {
libxsmm_wrapper(): libxsmm_mmfunction() {}
libxsmm_wrapper(int flags, int m, int n, int k, int lda, int ldb, int ldc, float alpha, float beta, int prefetch) :
libxsmm_mmfunction(flags, m, n, k, lda, ldb, ldc, alpha, beta, prefetch) {}
};
#endif
template<typename Dimensions, typename LhsXprType, typename RhsXprType>
struct traits<TensorContractionOp<Dimensions, LhsXprType, RhsXprType> >
@ -317,6 +381,8 @@ struct TensorContractionEvaluatorBase
}
}
EnableXSMMIfPossible(eval_op_indices);
// If the layout is RowMajor, we need to reverse the m_dimensions
if (static_cast<int>(Layout) == static_cast<int>(RowMajor)) {
for (int i = 0, j = NumDims - 1; i < j; i++, j--) {
@ -422,6 +488,13 @@ struct TensorContractionEvaluatorBase
template <bool lhs_inner_dim_contiguous, bool rhs_inner_dim_contiguous, bool rhs_inner_dim_reordered, int Alignment>
EIGEN_DEVICE_FUNC void evalGemm(Scalar* buffer) const {
#if defined(EIGEN_VECTORIZE_AVX) && defined(EIGEN_USE_LIBXSMM)
if (m_can_use_xsmm) {
evalGemmXSMM(buffer);
return;
}
#endif
// columns in left side, rows in right side
const Index k = this->m_k_size;
@ -538,7 +611,221 @@ struct TensorContractionEvaluatorBase
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar* data() const { return m_result; }
protected:
protected:
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void EnableXSMMIfPossible(const array<IndexPair<Index>, ContractDims>& eval_op_indices) {
m_can_use_xsmm = false;
#if defined(EIGEN_VECTORIZE_AVX) && defined(EIGEN_USE_LIBXSMM)
typedef typename internal::remove_const<typename EvalLeftArgType::Scalar>::type LhsScalar;
typedef typename internal::remove_const<typename EvalRightArgType::Scalar>::type RhsScalar;
if (!std::is_same<Scalar, LhsScalar>::value ||
!std::is_same<Scalar, RhsScalar>::value ||
!(std::is_same<Scalar, float>::value ||
std::is_same<Scalar, double>::value) ||
m_leftImpl.data() == NULL ||
m_rightImpl.data() == NULL) {
return;
}
// Check if we can use faster matmul algorithms. For contraction to be
// equivalent to matmul, we need both lhs and rhs contracting dims sequences
// to be either a prefix or suffix of all dims. Also, the order of both
// must be the same, so we don't have to do reordering.
// For example:
// * OK: lhs 4D, rhs 4D, contraction: [(0, 2), (1, 3)]
// * BAD: lhs 3D, rhs 3D, contraction: [(1,1)]
// * BAD: lhs 3D, rhs 3D, contraction: [(0, 0), (2, 2)]
// * BAD: lhs 3D, rhs 3D, contraction: [(0, 2), (1, 1)]
// Depending if contraction dims are prefix or suffix of all dims we need to
// pre-transpose matrices in matmul algorithm:
// lhs: prefix -> transpose, suffix -> no transpose
// rhs: prefix -> no transpose, suffix -> transpose
// For example, for lhs 2D, rhs 2D, contraction [(1, 0)] is regular,
// non-transposed matmul.
if (ContractDims == 0) {
// This case is totally uninteresting, filter it out to avoid problems
// with iterations in further tests.
return;
}
// Check if RHS dims list is increasing. LHS already is, so if not, the
// order is different and we cannot do matmul.
for (int i = 1; i < ContractDims; i++) {
if (eval_op_indices[i].second < eval_op_indices[i-1].second) {
return;
}
}
// Check if no holes.
int diff;
for (int i = 1; i < ContractDims; i++) {
// LHS contract dims are sorted to form an increasing seq.
diff = eval_op_indices[i].first - eval_op_indices[i-1].first;
if (diff != 1) {
return;
}
// Now we may already assume RHS contract dims seq is increasing too.
diff = eval_op_indices[i].second - eval_op_indices[i-1].second;
if (diff != 1) {
return;
}
}
// Check if suffix or prefix.
if (eval_op_indices[0].first != 0 &&
eval_op_indices[ContractDims-1].first != LDims-1) {
return;
}
if (eval_op_indices[0].second != 0 &&
eval_op_indices[ContractDims-1].second != RDims-1) {
return;
}
m_can_use_xsmm = true;
#endif
}
#if defined(EIGEN_VECTORIZE_AVX) && defined(EIGEN_USE_LIBXSMM)
EIGEN_DEVICE_FUNC void evalGemmXSMM(Scalar* buffer) const {
// columns in left side, rows in right side
const Index k = this->m_k_size;
// rows in left side
const Index m = this->m_i_size;
// columns in right side
const Index n = this->m_j_size;
const bool transposeA = !m_lhs_inner_dim_contiguous;
const bool transposeB = !m_rhs_inner_dim_contiguous;
typedef typename internal::remove_const<typename EvalLeftArgType::Scalar>::type LhsScalar;
typedef typename internal::remove_const<typename EvalRightArgType::Scalar>::type RhsScalar;
internal::TensorXsmmContractionBlocking<LhsScalar, RhsScalar, Index> blocking(
k, m, n, 1, transposeA, transposeB);
// Outer blocks sizes
const Index mc_outer = blocking.outer_m();
const Index nc_outer = blocking.outer_n();
const Index kc_outer = blocking.outer_k();
// Inner blocks sizes
const Index mc = blocking.mc();
const Index nc = blocking.nc();
const Index kc = blocking.kc();
// Decisions whether we should copy parts of matrices
const bool copyA = blocking.copyA();
const bool copyB = blocking.copyB();
const LhsScalar* leftData = m_leftImpl.data();
const RhsScalar* rightData = m_rightImpl.data();
libxsmm_blasint stride_A = static_cast<libxsmm_blasint>(transposeA ? k : m);
libxsmm_blasint stride_B = static_cast<libxsmm_blasint>(transposeB ? n : k);
libxsmm_blasint stride_C = static_cast<libxsmm_blasint>(m);
libxsmm_blasint stride_blockA = static_cast<libxsmm_blasint>(mc);
// Use bigger stride to avoid hitting same cache line too often.
// This consistently gives +~0.5 Gflops.
libxsmm_blasint stride_panelB = static_cast<libxsmm_blasint>(
kc % 32 == 0 ? kc + 16 : kc
);
// Kernel for the general case (not edges)
internal::libxsmm_wrapper<LhsScalar, RhsScalar, Scalar> kernel;
const LhsScalar *ap;
const RhsScalar *bp;
const Scalar *cp;
LhsScalar* blockA = NULL;
RhsScalar* panelB = NULL;
if (copyA) {
blockA = static_cast<LhsScalar*>(this->m_device.allocate(mc * kc * sizeof(LhsScalar)));
}
if (copyB) {
panelB = static_cast<RhsScalar*>(this->m_device.allocate(nc_outer * stride_panelB * sizeof(RhsScalar)));
}
Index kernel_stride_A = copyA ? stride_blockA : stride_A;
Index kernel_stride_B = copyB ? stride_panelB : stride_B;
kernel = internal::libxsmm_wrapper<LhsScalar, RhsScalar, Scalar>(0, mc, nc, kc, kernel_stride_A, kernel_stride_B, stride_C, 1, 1, blocking.prefetch());
// Outer blocking
for (Index ki_outer = 0; ki_outer < k; ki_outer += kc_outer) {
for (Index mi_outer = 0; mi_outer < m; mi_outer += mc_outer) {
for (Index ni_outer = 0; ni_outer < n; ni_outer += nc_outer) {
using numext::mini;
Index actual_nc_outer = mini(ni_outer+nc_outer, n) - ni_outer;
// Inner blocking
for (Index ki = ki_outer; ki < mini(ki_outer+kc_outer, k); ki += kc) {
const Index actual_kc = mini(ki_outer+kc_outer, mini(ki+kc, k)) - ki;
if (copyB) {
if (transposeB) {
libxsmm_otrans(panelB, rightData + ki*stride_B + ni_outer, sizeof(RhsScalar), actual_nc_outer, actual_kc, stride_B, stride_panelB);
} else {
internal::pack_simple<RhsScalar, Index>(panelB, rightData + ni_outer*stride_B + ki, actual_nc_outer, actual_kc, stride_panelB, stride_B);
}
}
for (Index mi = mi_outer; mi < mini(mi_outer+mc_outer, m); mi += mc) {
const Index actual_mc = mini(mi_outer+mc_outer, mini(mi+mc, m)) - mi;
const LhsScalar * a = transposeA ? leftData + mi*stride_A + ki :
leftData + ki*stride_A + mi;
if (copyA) {
if (transposeA) {
libxsmm_otrans(blockA, a, sizeof(LhsScalar), actual_kc, actual_mc, stride_A, stride_blockA);
} else {
internal::pack_simple<LhsScalar, Index>(blockA, a, actual_kc, actual_mc, stride_blockA, stride_A);
}
}
for (Index ni = ni_outer; ni < mini(ni_outer+nc_outer, n); ni += nc) {
const Index actual_nc = mini(ni_outer+nc_outer, mini(ni+nc, n)) - ni;
const RhsScalar * b = rightData + ni*stride_B + ki;
Scalar * c = buffer + ni*stride_C + mi;
cp = c + nc*stride_C;
const LhsScalar * actual_a = copyA ? blockA : a;
const Index actual_lda = copyA ? stride_blockA : stride_A;
ap = copyA ? blockA : a;
const RhsScalar * actual_b = copyB ? panelB + (ni-ni_outer)*stride_panelB : b;
const Index actual_ldb = copyB ? stride_panelB : stride_B;
bp = copyB ? panelB + nc*stride_panelB : b + nc*stride_B;
float beta = ki == 0 ? 0 : 1;
if (actual_mc == mc && actual_kc == kc && actual_nc == nc && beta == 1) {
// Most used, cached kernel.
kernel(actual_a, actual_b, c, ap, bp, cp);
} else {
// Edges - use libxsmm kernel cache.
internal::libxsmm_wrapper<LhsScalar, RhsScalar, Scalar>(0, actual_mc, actual_nc, actual_kc, actual_lda, actual_ldb, stride_C, 1, beta, blocking.prefetch())(actual_a, actual_b, c, ap, bp, cp);
}
}
}
}
}
}
}
if (copyA) {
this->m_device.deallocate(blockA);
}
if (copyB) {
this->m_device.deallocate(panelB);
}
}
#endif
// Prevent assignment
TensorContractionEvaluatorBase& operator = (const TensorContractionEvaluatorBase&);
Dimensions m_dimensions;
@ -567,6 +854,7 @@ struct TensorContractionEvaluatorBase
/// required for sycl
const Indices m_expr_indices;
bool m_can_use_xsmm;
};
@ -624,7 +912,6 @@ struct TensorEvaluator<const TensorContractionOp<Indices, LeftArgType, RightArgT
this->template evalGemm<lhs_inner_dim_contiguous, rhs_inner_dim_contiguous, rhs_inner_dim_reordered, Alignment>(buffer);
}
};
} // end namespace Eigen

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@ -50,6 +50,140 @@ class TensorContractionBlocking {
};
#if defined(EIGEN_USE_LIBXSMM)
template <typename LhsScalar, typename RhsScalar, typename Index>
class TensorXsmmContractionBlocking {
public:
TensorXsmmContractionBlocking(Index k, Index m, Index n,
size_t max_num_threads = 1, bool transposeA = false,
bool transposeB = false):
k_(k), m_(m), n_(n), transposeA_(transposeA),
transposeB_(transposeB), num_threads_(max_num_threads) {
#ifdef EIGEN_TEST_SPECIFIC_BLOCKING_SIZES
if (EIGEN_TEST_SPECIFIC_BLOCKING_SIZES) {
mc_ = EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_M;
kc_ = EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_K;
nc_ = EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_N;
outer_m_ = EIGEN_TEST_SPECIFIC_OUTER_BLOCKING_SIZE_M;
outer_k_ = EIGEN_TEST_SPECIFIC_OUTER_BLOCKING_SIZE_K;
outer_n_ = EIGEN_TEST_SPECIFIC_OUTER_BLOCKING_SIZE_N;
copyA_ = EIGEN_TEST_SPECIFIC_BLOCKING_COPY_A;
copyB_ = EIGEN_TEST_SPECIFIC_BLOCKING_COPY_B;
outer_m_ = outer_m_ != 0 ? outer_m_ : m;
outer_k_ = outer_k_ != 0 ? outer_k_ : k;
outer_n_ = outer_n_ != 0 ? outer_n_ : n;
}
#else
// Defaults, possibly overriden per-platform.
copyA_ = true;
copyB_ = false;
// If the matrix is small enough, don't do blocking, just call single xsmm
// kernel.
if (static_cast<double>(m)*k*n <= LIBXSMM_THRESHOLD) {
mc_ = m; kc_ = k; nc_ = n;
outer_m_ = m; outer_k_ = k; outer_n_ = n;
copyA_ = false; copyB_ = false;
} else {
int arch = libxsmm_cpuid_x86();
if (arch == LIBXSMM_X86_AVX512_CORE) {
// skylake
mc_ = 64; kc_ = 64; nc_ = 24;
outer_m_ = 512; outer_k_ = 512; outer_n_ = 24*22;
// Hack to use this kernel architecture as the other one has performance
// issues (no hardware prefetching).
// TODO(nishantpatil): This should be removed if the issues are fixed,
// or this one becomes the default.
setenv("LIBXSMM_AVX512_CLASSIC_GEMM", "1", 1);
} else if (arch == LIBXSMM_X86_AVX2) {
// haswell
mc_ = 32; kc_ = 192; nc_ = 33;
outer_m_ = 512; outer_k_ = 3*192; outer_n_ = 33*16;
} else if (arch == LIBXSMM_X86_AVX) {
// ivybridge
mc_ = 32; kc_ = 192; nc_ = 48;
outer_m_ = 512; outer_k_ = 3*192; outer_n_ = 48*11;
} else {
// generic kernel size, usually performing well
mc_ = 32; kc_ = 128; nc_ = 32;
outer_m_ = 512; outer_k_ = 512; outer_n_ = 512;
}
// Only copy if it makes the stride smaller.
copyA_ = copyA_ && (m > mc_);
copyB_ = copyB_ && (k > kc_);
}
// We need to copy anyway if transposing
copyA_ = copyA_ || transposeA;
copyB_ = copyB_ || transposeB;
// See libxsmm_gemm_prefetch_type definition in libxsmm_typedefs.h
prefetch_ = LIBXSMM_PREFETCH_AL2CL2BL2_VIA_C;
#endif
mc_ = mc_ > m ? m : mc_;
nc_ = nc_ > n ? n : nc_;
kc_ = kc_ > k ? k : kc_;
size_t compute_parallelism = (m / mc_) * (n / nc_);
size_t pack_parallelism = 0;
if (copyA_) {
pack_parallelism += (m / mc_) * (k / kc_);
}
if (copyB_) {
pack_parallelism += (n / nc_) * (k / kc_);
}
size_t parallelism = numext::maxi(compute_parallelism, pack_parallelism);
num_threads_ = numext::mini<size_t>(num_threads_,
parallelism / MIN_JOBS_PER_THREAD);
num_threads_ = numext::maxi<size_t>(num_threads_, 1);
// For optimal performance outer block sizes should be multiplies of kernel
// sizes, or bigger than matrix size (=no outer blocking).
eigen_assert(outer_m_ % mc_ == 0 || outer_m_ >= m);
eigen_assert(outer_k_ % kc_ == 0 || outer_k_ >= k);
eigen_assert(outer_n_ % nc_ == 0 || outer_n_ >= n);
}
EIGEN_ALWAYS_INLINE Index kc() const { return kc_; }
EIGEN_ALWAYS_INLINE Index mc() const { return mc_; }
EIGEN_ALWAYS_INLINE Index nc() const { return nc_; }
EIGEN_ALWAYS_INLINE Index outer_k() const { return outer_k_; }
EIGEN_ALWAYS_INLINE Index outer_m() const { return outer_m_; }
EIGEN_ALWAYS_INLINE Index outer_n() const { return outer_n_; }
EIGEN_ALWAYS_INLINE bool copyA() const { return copyA_; }
EIGEN_ALWAYS_INLINE bool copyB() const { return copyB_; }
EIGEN_ALWAYS_INLINE bool transposeA() const { return transposeA_; }
EIGEN_ALWAYS_INLINE bool transposeB() const { return transposeB_; }
EIGEN_ALWAYS_INLINE int num_threads() const { return num_threads_; }
EIGEN_ALWAYS_INLINE Index blocks_m() const { return divup(m_, mc_); }
EIGEN_ALWAYS_INLINE Index blocks_k() const { return divup(k_, kc_); }
EIGEN_ALWAYS_INLINE Index blocks_n() const { return divup(n_, nc_); }
EIGEN_ALWAYS_INLINE libxsmm_gemm_prefetch_type prefetch() const {
return prefetch_;
}
private:
Index k_, m_, n_;
Index kc_, mc_, nc_;
Index outer_k_, outer_m_, outer_n_;
bool copyA_, copyB_, transposeA_, transposeB_;
size_t num_threads_;
// Threshold for m*k*n to skip blocking and just call libxsmm
const double LIBXSMM_THRESHOLD = 80*80*80;
// For computing optimal number of threads - so that each thread gets at least
// that many jobs.
const double MIN_JOBS_PER_THREAD = 3;
libxsmm_gemm_prefetch_type prefetch_;
};
#endif // EIGEN_USE_LIBXSMM
} // end namespace internal
} // end namespace Eigen