Perf: pin Graph PODs and H2D each layer synchronously

[yanghaoran29]

Summary

• Based on latest perf/hbg-orch (not main, not PR Perf: reuse retained temp for HBG bind.args staging #1854).
• During host orchestration, each Graph layer POD is written into a retained 16MB pinned host arena (aclrtMallocHost) and copy_to_device'd as soon as that layer is ready.
• Device POD buffers are retained per (graph_key, occurrence) and not freed in validate.
• Bind-stage STRACE / strace_timing changes are intentionally omitted; they stay measurement-only.

Test plan

• examples/a2a3/host_build_graph/qwen3_14b_decode onboard --skip-golden
• Confirm Graph H2D is per-layer during orch entry (no post-orch gather of unpinned images)

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📝 Walkthrough

Walkthrough

Graph submission uploads now use a pinned host arena, eager H2D callbacks, and retained device buffers. Submission images fall back to vectors when needed, duplicate uploads are skipped, and leftover submissions use the shared upload path.

Changes

Graph upload lifecycle

Layer / File(s)	Summary
Pinned submission image construction src/common/host_build_graph/graph_host_state.h, src/a2a3/runtime/host_build_graph/runtime/orchestrator_core/pto_orchestrator.cpp	Graph host state adds pinned-arena and H2D completion APIs. Submission images use aligned pinned storage when available and vector-backed storage otherwise.
Eager upload callback path src/a2a3/runtime/host_build_graph/runtime/orchestrator_core/pto_orchestrator.cpp, src/a2a3/runtime/host_build_graph/host/runtime_maker.cpp	Pending submissions invoke the configured eager upload callback. The callback tracks H2D completion and is disabled after orchestration.
Retained device upload orchestration src/a2a3/runtime/host_build_graph/host/runtime_maker.cpp	GraphPodH2d reuses retained device submission buffers, skips completed uploads, processes leftover submissions, and manages pinned-arena cleanup through RAII.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟠 High · up to f9809

This change performs per-layer pinned host writes and immediate device uploads, but the current implementation can leave invalid graph state after upload failures, reuse device buffers across unrelated graphs or runtime lifetimes, and corrupt uploads when orchestrations overlap. These high-impact correctness and availability risks should be fixed before merging.

Sequence Diagram(s)

sequenceDiagram
  participant HostOrchestration
  participant SubmissionBuilder
  participant GraphHostState
  participant GraphPodH2d
  participant DeviceBuffer
  HostOrchestration->>SubmissionBuilder: build graph submission image
  SubmissionBuilder->>GraphHostState: register pending upload
  GraphHostState->>GraphPodH2d: invoke eager upload callback
  GraphPodH2d->>DeviceBuffer: reuse or allocate retained buffer
  GraphPodH2d->>GraphHostState: mark H2D upload complete

Loading

Possibly related PRs

• hw-native-sys/simpler#1870: Overlaps with the pinned-arena, eager-upload, retained-buffer, and completion logic.
• hw-native-sys/simpler#1854: Also changes retained device staging allocations and duplicate H2D upload handling.
• hw-native-sys/simpler#1813: Introduces shared GraphHostState APIs extended by this change.

Poem

A rabbit packs each graph with care,
Into a pinned and speedy lair.
Buffers stay when binds return,
Duplicate hops no longer churn.
H2D flags glow, then uploads rest.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 3.85% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main changes: pinned Graph PODs and synchronous per-layer H2D uploads.
Description check	✅ Passed	The description directly explains the pinned arena, synchronous H2D uploads, retained device buffers, scope, and test plan.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

⚔️ Resolve merge conflicts 💡

• Resolve merge conflict in branch perf/hbg-orch-pinned-h2d

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[yanghaoran29]

设计理念

对比对象是 perf/hbg-orch 当前的 Graph POD 上传路径。

perf/hbg-orch 上每层会产出一份较小的 POD 镜像（qwen 大约几十层 × ~100KB 量级）。构图在 entry() 里按层推进，但 H2D 被攒到构图全部结束之后：

1. graph_submit_definition 把该层 POD 写进普通 std::vector（pageable host 内存），只登记进 pending_uploads。
2. entry() 返回后，upload_graph_submissions 再逐层 device_malloc + copy_to_device（底层是 rtMemcpy H2D）。
3. 这些 device 指针进 tensor_pairs_，validate 每轮 device_free。

稳态税来自两处：H2D 源是 pageable vector、每轮重新 staging；device POD 每轮 malloc/拷/free。构图算法本身不用改。

本 PR 的理念是让 「层就绪」和「该层上卡」变成同一件事（compute-one-layer, copy-that-layer）：构图仍按 perf/hbg-orch 的层序走，只是层一 fill 完就同步 H2D，并且源地址已经是 pinned。

Pinned 是什么、为什么能变快

Pinned（page-locked）host 内存：本 PR 用 aclrtMallocHost 拿到的那块 16MB arena。操作系统把这些页锁在物理 RAM 里，不会被换出；NPU DMA 可以直接按物理地址从 host 读。

perf/hbg-orch 用的 std::vector 是 pageable 的：malloc/new 出来的页随时可能不在物理内存里。rtMemcpy(H2D) 不能假定 DMA 能直接读它，运行时通常会：

• 先把这段数据拷进驱动内部的 pinned bounce buffer，再 DMA 上卡；或
• 临时 pin 这几页，拷完再 unpin。

无论哪条，一次 copy_to_device 都会多付 CPU 侧的准备成本。Graph 路径是几十次小拷贝（每层一份 POD），这个额外成本会按层数放大。源改成已经 pin 好的地址后，每次 rtMemcpy 可以直接 DMA，少掉 bounce / 临时 pin。

另外这块 16MB 跨 round 复用：aclrtMallocHost 本身也不便宜，稳态轮不再每 bind 申请一次。orch 只是 bump 指针把 POD 写进已有 arena，H2D 源始终是同一块 pinned 基址上的切片。

Pinned 不会让 DMA 带宽 magically 变大，也不是把 40 层合成一次大拷贝；变快的是 每次小 H2D 的启动开销 + 去掉 pageable staging。

设计思路

三条正交的保留/就地写，只动 Graph POD，不碰 Args / SM / arena。

1. Host pinned bump（跨 round 复用）

aclrtMallocHost 一块 16MB arena，绑在 g_graph_pack 上，只在首次（或容量不够）时分配，之后每轮复用。orch 前 graph_host_set_pinned_arena，结束 RAII graph_host_clear_pinned_arena。

graph_submit_definition 用 bump 把该层 POD 直接写进 pinned 地址。H2D 源就是这块内存，不再走 perf/hbg-orch 的 std::vector staging。写不下时回退到原来的 vector 路径，功能不错。

2. Eager 同步 H2D（一层一拷）

相对 perf/hbg-orch「构图全部完成 → 再循环 copy_to_device」，这里在 pending_uploads.push_back 之后立刻回调 host runtime。GraphPodH2d::upload_one 补 execution_storage、拿 device POD、同步 copy_to_device，然后标 h2d_done。

层与层之间本身有构图间隔；把该层拷贝放在「刚 fill 完」的点上，CPU 构图和 DMA 按层交替，而不是几十次拷贝挤在 orch 结束后的一个突发窗口。同步 copy_to_device 保持和 perf/hbg-orch 相同的拷贝原语，只改调用时机和源地址是否 pinned。

entry() 结束后再扫 leftover（h2d_done == false）。稳态 hook 命中时应为 0，这是兜底。

3. Device POD 跨 round retain

perf/hbg-orch 每轮 malloc/free。这里按 (graph_key, occurrence) 缓存 device buffer：尺寸不变则只付 H2D。这些指针不进 tensor_pairs_，避免 validate 每轮 device_free。

数据流（稳态一轮）

ensure pinned 16MB (reuse)
    → graph_host_set_pinned_arena
    → set eager hook
    → entry():
         per layer: bump POD into pinned → upload_one() → rtMemcpy H2D (src already pinned)
    → leftover scan (steady: 0)
    → relocate / h2d_sm / h2d_arena（与 perf/hbg-orch 相同）

perf/hbg-orch 则是 entry() 只填 vector，返回后再 upload_graph_submissions 逐层 malloc + pageable H2D。

明确不做的

• 不改 Args 路径，不依赖 PR Perf: reuse retained temp for HBG bind.args staging #1854。
• 不把 bind 细打点 / strace_timing 改动放进本 PR（测量用，不入库）。
• a5 的 HBG 副本未改；本 PR 只动 a2a3 host_build_graph。

测量口径（不在本 PR 代码里）

同卡交叉、各 50 次、5 次一交叉，每段去掉最高 10 / 最低 10 再平均。相对 perf/hbg-orch 基线（构图完再逐层 pageable H2D），稳态 Gate 约 3.07 → 2.72 ms，其中 H2dGraph 1.06 → 0.74 ms；HostOrch 基本持平。

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Inline comments:
In `@src/a2a3/runtime/host_build_graph/host/runtime_maker.cpp`:
- Around line 467-490: Update acquire_submission and retained_subs so retained
submissions belong to the owning runtime or device resource rather than
process-lifetime static state; key entries with separate uint64_t graph_key and
uint32_t occurrence fields instead of a lossy packed key, and release every
retained device allocation during that owner’s teardown.

In
`@src/a2a3/runtime/host_build_graph/runtime/orchestrator_core/pto_orchestrator.cpp`:
- Around line 1625-1630: The eager-upload failure path in the orchestration
function must latch a fatal orchestration error after the GRAPH slot and pending
upload have been published, rather than returning false for ordinary fallback.
Update the g_eager_upload_fn failure handling to record the fatal state and
abort graph_begin’s fallback path while preserving successful uploads.
- Around line 352-385: Make graph upload callbacks and pinned-arena bookkeeping
run-scoped rather than process-global: in
src/a2a3/runtime/host_build_graph/runtime/orchestrator_core/pto_orchestrator.cpp:352-385,
move the callback/context and bump allocator state into an orchestration-owned
object; update the GraphHostState configuration API in
src/common/host_build_graph/graph_host_state.h:41-52 to carry that run-owned
state; and in src/a2a3/runtime/host_build_graph/host/runtime_maker.cpp:618-629,
use RAII to clear the callback on every exit and prevent overlapping runs from
sharing the pinned arena.

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• src/a2a3/runtime/host_build_graph/host/runtime_maker.cpp
• src/a2a3/runtime/host_build_graph/runtime/orchestrator_core/pto_orchestrator.cpp
• src/common/host_build_graph/graph_host_state.h

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