Manual control of MAC cluster for improved interwave performance (#184)

* manual control of MAC cluster for improved 2-wave performance

ensure setprio's order; ensure inner loop size >= local read size

synchronize when single mac cluster

* format

* use value field from ck::integral_constant

* roll out inter-wave loop scheduler to c-shuffle gemm variants

will gradually roll out to other applicable device ops when occasional reg spill is resolved

* additional comments

* format

* fix mismatch between inter-wave pipeline and interwave blockwise gemm

* address review feedback

* amend
This commit is contained in:
Anthony Chang
2022-05-11 08:19:22 +08:00
committed by GitHub
parent 712e464c4e
commit 76764d8c92
8 changed files with 446 additions and 61 deletions

View File

@@ -7,6 +7,21 @@
namespace ck {
enum struct LoopScheduler
{
Default,
Interwave,
};
constexpr LoopScheduler make_default_loop_scheduler()
{
#if CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING
return LoopScheduler::Interwave;
#else
return LoopScheduler::Default;
#endif // if CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING
}
template <index_t BlockSize,
typename FloatAB,
typename FloatAcc,
@@ -302,7 +317,7 @@ struct BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1
});
}
private:
protected:
// A[M0, M1, M2, KPerThread]
static constexpr auto a_thread_desc_ =
make_naive_tensor_descriptor_packed(make_tuple(I1, I1, I1, Number<KPerThread>{}));
@@ -339,4 +354,232 @@ struct BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1
BThreadCopy b_thread_copy_{CalculateBThreadOriginDataIndex()};
};
// Note: To facilitate the inter-wave loop scheduler, we need to explicitly set the macro
// CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING=1 as a few intrinsics are not yet available in
// the latest ROCm release. For unsupported compilers, inter-wave loop scheduler falls back to the
// default loop scheduler which is given by the macro CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING=0
template <index_t BlockSize,
typename FloatAB,
typename FloatAcc,
typename AK0MK1BlockDesc,
typename BK0NK1BlockDesc,
index_t MPerXDL,
index_t NPerXDL,
index_t MRepeat,
index_t NRepeat,
index_t KPack,
index_t NumMacClusters = CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING_MAC_CLUSTERS>
struct BlockwiseGemmXdlopsInterwave_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1
: public BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1<BlockSize,
FloatAB,
FloatAcc,
AK0MK1BlockDesc,
BK0NK1BlockDesc,
MPerXDL,
NPerXDL,
MRepeat,
NRepeat,
KPack>
{
using Base = BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1<BlockSize,
FloatAB,
FloatAcc,
AK0MK1BlockDesc,
BK0NK1BlockDesc,
MPerXDL,
NPerXDL,
MRepeat,
NRepeat,
KPack>;
#if CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING
using Base::a_block_desc_m0_m1_m2_k;
using Base::A_K1;
using Base::b_block_desc_n0_n1_n2_k;
using Base::B_K1;
using Base::c_thread_buf_;
using Base::c_thread_desc_;
using Base::CalculateAThreadOriginDataIndex;
using Base::CalculateBThreadOriginDataIndex;
using Base::I0;
using Base::I1;
using Base::KPerThread;
using Base::xdlops_gemm;
static constexpr index_t KPerInnerLoop = math::max(KPerThread / NumMacClusters, KPack);
// 2-wave optimized blockwise gemm
template <typename ABlockBuffer, typename BBlockBuffer, typename CThreadBuffer>
__device__ void Run(const ABlockBuffer& a_block_buf,
const BBlockBuffer& b_block_buf,
CThreadBuffer& c_thread_buf) const
{
auto a_thread_buf = make_static_buffer<AddressSpaceEnum::Vgpr, FloatAB>(
a_thread_desc_.GetElementSpaceSize());
auto b_thread_buf = make_static_buffer<AddressSpaceEnum::Vgpr, FloatAB>(
b_thread_desc_.GetElementSpaceSize());
static_for<0, KPerThread, KPerInnerLoop>{}([&](auto k) {
static_for<0, MRepeat, 1>{}([&](auto m0) {
// read A
a_thread_copy_.Run(a_block_desc_m0_m1_m2_k,
make_tuple(m0, I0, I0, k),
a_block_buf,
a_thread_desc_,
make_tuple(m0, I0, I0, I0),
a_thread_buf);
});
static_for<0, NRepeat, 1>{}([&](auto n0) {
// read B
b_thread_copy_.Run(b_block_desc_n0_n1_n2_k,
make_tuple(n0, I0, I0, k),
b_block_buf,
b_thread_desc_,
make_tuple(n0, I0, I0, I0),
b_thread_buf);
});
__builtin_amdgcn_sched_barrier();
// NOTE: Synchronize threads in a workgroup at the start of each MAC cluster, but except
// the first, as we can shorten non-MAC cluster a bit and there's no observable negative
// impact. The desired effect is waves in a workgroup executing MAC in sync. This avoids
// some out-of-sync waves hijacking MAC resource from other workgroups and reducing the
// chance of latency hiding by waiting for the rest of the workgroup at the eventual
// sync point.
if constexpr(k.value != 0 || KPerInnerLoop == KPerThread)
{
asm volatile("s_barrier" ::);
__builtin_amdgcn_sched_barrier();
}
static_for<0, KPerInnerLoop, KPack>{}([&](auto k_) {
static_for<0, MRepeat, 1>{}([&](auto m0) {
static_for<0, NRepeat, 1>{}([&](auto n0) {
vector_type<FloatAB, KPack> a_thread_vec;
vector_type<FloatAB, KPack> b_thread_vec;
static_for<0, KPack, 1>{}([&](auto i) {
a_thread_vec.template AsType<FloatAB>()(i) =
a_thread_buf[Number<a_thread_desc_.CalculateOffset(
make_tuple(m0, 0, 0, k_ + i))>{}];
b_thread_vec.template AsType<FloatAB>()(i) =
b_thread_buf[Number<b_thread_desc_.CalculateOffset(
make_tuple(n0, 0, 0, k_ + i))>{}];
});
using mfma_input_type =
typename vector_type<FloatAB, xdlops_gemm.K1PerXdlops>::type;
constexpr index_t c_offset =
c_thread_desc_.CalculateOffset(make_tuple(m0, n0, 0));
// The block_sync_lds() here performs double duty:
// A) safeguard against data hazard because barrier from blockwise_gemm is
// moved here B) reduce VMEM FIFO congestion by applying small delays to
// different wavefronts It is performed near the end of MAC cluster to
// minimize lgkmcnt penalty
if constexpr(k.value == KPerThread - KPerInnerLoop &&
k_.value == KPerInnerLoop - KPack && m0.value == MRepeat - 1 &&
n0.value == NRepeat - 1)
{
__builtin_amdgcn_sched_barrier();
block_sync_lds();
__builtin_amdgcn_sched_barrier();
}
// TODO: insert setprio in more precise manner since we
// could have more than >1 MFMA instructions in single call
xdlops_gemm.template Run(
a_thread_vec.template AsType<mfma_input_type>(),
b_thread_vec.template AsType<mfma_input_type>(),
c_thread_buf.GetVectorTypeReference(Number<c_offset>{}));
if constexpr(k_.value == 0 && m0.value == 0 && n0.value == 0)
{
__builtin_amdgcn_sched_barrier();
__builtin_amdgcn_s_setprio(1);
__builtin_amdgcn_sched_barrier();
}
});
});
});
__builtin_amdgcn_sched_barrier();
__builtin_amdgcn_s_setprio(0);
__builtin_amdgcn_sched_barrier();
});
}
protected:
// A[M0, M1, M2, KPerInnerLoop]
static constexpr auto a_thread_desc_ = make_naive_tensor_descriptor_packed(
make_tuple(Number<MRepeat>{}, I1, I1, Number<KPerInnerLoop>{}));
// B[N0, N1, N2, KPerInnerLoop]
static constexpr auto b_thread_desc_ = make_naive_tensor_descriptor_packed(
make_tuple(Number<NRepeat>{}, I1, I1, Number<KPerInnerLoop>{}));
using AThreadCopy = ThreadwiseTensorSliceTransfer_v4<FloatAB,
FloatAB,
decltype(a_block_desc_m0_m1_m2_k),
decltype(a_thread_desc_),
Sequence<1, 1, 1, KPerInnerLoop>,
Sequence<0, 1, 2, 3>,
3,
A_K1,
A_K1>;
using BThreadCopy = ThreadwiseTensorSliceTransfer_v4<FloatAB,
FloatAB,
decltype(b_block_desc_n0_n1_n2_k),
decltype(b_thread_desc_),
Sequence<1, 1, 1, KPerInnerLoop>,
Sequence<0, 1, 2, 3>,
3,
B_K1,
B_K1>;
AThreadCopy a_thread_copy_{CalculateAThreadOriginDataIndex()};
BThreadCopy b_thread_copy_{CalculateBThreadOriginDataIndex()};
#endif // #if CK_EXPERIMENTAL_INTER_WAVE_SCHEDULING
};
template <index_t BlockSize,
typename FloatAB,
typename FloatAcc,
typename AK0MK1BlockDesc,
typename BK0NK1BlockDesc,
index_t MPerXDL,
index_t NPerXDL,
index_t MRepeat,
index_t NRepeat,
index_t KPack,
LoopScheduler LoopSched>
constexpr auto BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_Selector()
{
if constexpr(LoopSched == LoopScheduler::Default)
{
return BlockwiseGemmXdlops_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1<BlockSize,
FloatAB,
FloatAcc,
AK0MK1BlockDesc,
BK0NK1BlockDesc,
MPerXDL,
NPerXDL,
MRepeat,
NRepeat,
KPack>{};
}
else if constexpr(LoopSched == LoopScheduler::Interwave)
{
return BlockwiseGemmXdlopsInterwave_k0mk1_k0nk1_m0n0m1n1m2m3m4n2_v1<BlockSize,
FloatAB,
FloatAcc,
AK0MK1BlockDesc,
BK0NK1BlockDesc,
MPerXDL,
NPerXDL,
MRepeat,
NRepeat,
KPack>{};
}
};
} // namespace ck