PE_IPCQ._handle_recv now yields-from _delayed_credit_send instead of
spawning it as a fork, so the receiver's pe_exec_ns includes the
credit-return cost. _credit_latency_ns switches from
compute_drain_ns(path, 16) to compute_path_latency_ns(path, 16) and
fixes a latent find_path bug where the destination lacked the
".pe_dma" suffix (silently returned 0 ns under the bare except).
Net effect on h3/h4 inter-cube pe-to-pe latency: IPCQ >= raw DMA at
every size, matching real-HW posted-write semantics. tl.send remains
fire-and-forget. ADR-0023 D9 amended; new diagnostic test
tests/test_pe_to_pe_diagnostic.py captures per-PE pe_exec_ns, paths,
drain, and meta-arrival timing.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- KernelLaunchMsg gains target_start_ns: IO_CPU stamps a global barrier
(max path latency across every target PE), M_CPU passes it through,
PE_CPU yields until it before recording pe_exec_start. Every PE in a
launch begins kernel execution at the same env.now regardless of its
dispatch path length — eliminates per-PE dispatch-offset artifact in
cross-PE and cross-cube latency measurements.
- PE_DMA._handle_ipcq_inbound now pays Transaction.drain_ns at the top,
matching the terminal-drain behavior of ComponentBase._forward_txn for
every non-IPCQ Transaction. SRC-side tl.send stays fire-and-forget
(sender doesn't yield on sub_done); tl.recv now blocks until bytes
have actually drained into its inbox.
- ComponentContext: new compute_path_latency_ns helper + node_overhead_ns
field populated by GraphEngine.
- tests/test_kernel_launch_sync.py: asserts all PEs in one launch
produce identical pe_exec_ns for a no-op kernel (zero spread).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
mukesh
ywkang