In "sm100_mma_warpspecialized.hpp", why does load() pre-issue producer_try_acquire for the next stage before launching TMA copies for the current stage

[RiseJia]

In line 581 - 628，the below source code

  /// Perform a collective-scoped matrix multiply-accumulate
  /// Producer Perspective
  template <
    class LoadParams,
    class TileCoordMNKL,
    class KTileIterator
  >
  CUTLASS_DEVICE auto
  load(
    MainloopPipeline mainloop_pipeline,
    MainloopPipelineState mainloop_pipe_producer_state,
    LoadParams const& load_inputs,
    TileCoordMNKL const& cta_coord_mnkl,
    KTileIterator k_tile_iter, int k_tile_count) {

    auto [unused_k_tiles,
          tAgA_mkl, tBgB_nkl, tAsA, tBsB,
          mcast_mask_a, mcast_mask_b] = load_inputs;

    // slice out the work coord from partitioned tensors
    Tensor tAgA = tAgA_mkl(_, get<0>(cta_coord_mnkl) / size(typename TiledMma::AtomThrID{}), _, get<3>(cta_coord_mnkl));
    Tensor tBgB = tBgB_nkl(_, get<1>(cta_coord_mnkl), _, get<3>(cta_coord_mnkl));

    auto barrier_token = mainloop_pipeline.producer_try_acquire(mainloop_pipe_producer_state); // try_wait stage 0

    // Issue the Mainloop loads
    CUTLASS_PRAGMA_NO_UNROLL
    while (k_tile_count > 0) {
      // LOCK mainloop_pipe_producer_state for _writing_
      mainloop_pipeline.producer_acquire(mainloop_pipe_producer_state, barrier_token); // try_wait_spin stage 0 

      using BarrierType = typename MainloopPipeline::ProducerBarrierType;
      BarrierType* tma_barrier = mainloop_pipeline.producer_get_barrier(mainloop_pipe_producer_state);

      int write_stage = mainloop_pipe_producer_state.index();
      ++mainloop_pipe_producer_state; // state++
      // Q: Why copy stage 0 after try_wait stage 1?
      barrier_token = mainloop_pipeline.producer_try_acquire(mainloop_pipe_producer_state); // try_wait stage 1

      if (cute::elect_one_sync()) {
        copy(observed_tma_load_a_->with(*tma_barrier, mcast_mask_a), tAgA(_,*k_tile_iter), tAsA(_,write_stage)); // copy stage 0
        copy(observed_tma_load_b_->with(*tma_barrier, mcast_mask_b), tBgB(_,*k_tile_iter), tBsB(_,write_stage)); // copy stage 0
      }

      --k_tile_count;
      ++k_tile_iter;
    }

    return cute::make_tuple(mainloop_pipe_producer_state, k_tile_iter);
  }

First of all, thank for your fantasic work and documentation. While reading this particular load implementation, I have couple questions:

• Ordering: What’s the rationale for calling producer_try_acquire(state /N+1/) before issuing stage N TMA copies? Is this required for correctness, or a latency-hiding choice (pre-fetching the next barrier token to make the next producer_acquire likely immediate)? Are there any microarchitectural considerations?
• PTX “may suspend” : PTX says a try_wait can be “potentially suspended.” How should we interpret this in practice—does it yield the warp/scoreboard briefly vs. pure non-blocking polling?

Could you please help me to clarify my questions? Appreciate any explain.