Commit Graph

7 Commits

Author SHA1 Message Date
kzlin
7590e55189 docs: archive deprecated docs to docs/archive/, drop E1 from onboarding
Two cleanups:

1. Drop "E1: naive 1P3D default" experiment from the onboarding manual.
   GPU hours are precious; naive 1P3D + policy=default has near-certain
   loss on multi-turn cache hit (it's round-robin without prefix awareness),
   so the comparison doesn't add information vs E1=naive 1P3D kv-aware.
   The new manifest has only 2 runs: E1 (naive 1P3D kv-aware) + E2 (KVC
   v2 + RDMA). Run-time budget drops from 16.5h serial to 11h serial /
   5.5h parallel. Updated:
   - §0 TL;DR ("3 组" -> "2 组")
   - §2 H1 hypothesis (drop "default and kv-aware each one" -> just kv-aware)
   - §3.1 experiment matrix (3 rows -> 2 rows + rationale for the drop)
   - §3.2 startup config (drop E1 default section, renumber E2/E3 -> E1/E2)
   - §6 decision table + expected-range table
   - §7 FAQ ("3 个 E1-E3" -> "2 个 E1-E2")
   - §9 deliverables

2. Move 8 deprecated docs to docs/archive/:
     AGENTIC_FIT_ANALYSIS_ZH.md         (ts=10 era analysis; superseded)
     STRUCTURAL_VALIDATION_REPORT_ZH.md (ts=10 era validation; superseded)
     KVC_DEBUG_JOURNEY_V1_TO_V5.md      (v1-v5 sweep process notes)
     V5_PROFILE_INVESTIGATION_ZH.md     (v5 1Hz polling investigation)
     REFACTOR_PLAN_ZH.md                (v0 plan; superseded by V1)
     KVCACHE_CENTRIC_PROGRESS_ZH.md     (earliest 2026-04-27 progress)
     SWEBENCH_EXPERIMENT_PROGRESS.md    (early SWE trace setup)
     SWEBENCH_EXPERIMENT_RESULTS.md     (early SWE result snapshot)

   All cross-references in active docs (V2_DEEP_ANALYSIS / V2_RESULTS /
   REFACTOR_PLAN_V1 / TEAM_REPORT / ONBOARDING) rewritten from
   `docs/FOO.md` to `docs/archive/FOO.md` via sed pass.

   Added `docs/archive/README.md` explaining what each archived doc is
   and when (if ever) to reopen it. Designed so a new reader hitting
   the archive dir immediately knows it's not required reading.

After this commit the active docs in docs/ are 9 files (down from 17),
which should make the onboarding doc's "Level 1 / Level 2 / Level 3"
classification self-evident.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 22:40:35 +08:00
kzlin
9ccd853066 docs(kvc): correct reseed cost decomposition + flag D->P sync gap
After an independent Opus-agent forensic audit, the previous "(c) 增量
fetch (工程量较大,未实现)" line in V2_DEEP_ANALYSIS §4.2 was understating
the gap. The audit confirmed:

- No D->P KV transfer code exists in the framework at any layer
  (agentic_pd_hybrid orchestration, vendored SGLang disaggregation,
  or mooncake transport).
- Mooncake MooncakeKVManager has a hard role split: PREFILL = sender,
  DECODE = receiver-only loop. `add_transfer_request` asserts the
  disaggregation_mode is PREFILL.
- The BaseKVSender / BaseKVReceiver abstraction has no bidirectional slot.
- session_aware_cache.release_session only calls kv_pool_allocator.free()
  on eviction -- no serialization, no outbound network call.
- _commit_prefill_backup_residency is only called from the seed/reseed
  path (_invoke_kvcache_seeded_router). direct-to-D path never updates
  P-side backup state.
- "capacity-backup" policy semantics: it only skips the close on P after
  reseed -- the backup is the seed-time static snapshot, never refreshed
  by D-side append-prefill activity.

V2_DEEP_ANALYSIS §4.2:
- Decomposed the 3-7s reseed cost into the P-side re-prefill segment
  (1.5-3s, dominant) and the P->D mooncake transfer segment (1.5-4s).
- Quantified the realistic effect of enabling RDMA: only the transfer
  segment shrinks, reseed reduces to 1.7-3.2s, TTFT p99 ~0.7s, still
  loses to DP's 0.43s.
- Replaced the throwaway "(c) incremental fetch" line with a full
  paragraph explaining what D->P sync would require, why it's the
  largest engineering gap, and that the blocker is SGLang's radix-tree
  single-producer assumption, not the network layer.

KVC_ROUTER_ALGORITHM §9:
- Refined Open Question 3 (RDMA) to clarify it only helps the transfer
  segment, not the re-prefill segment.
- Added Open Question 4: D->P incremental KV sync as the central
  future-work contribution gap, with cited evidence for why it doesn't
  currently exist.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 22:07:14 +08:00
kzlin
517677d7f2 docs(kvc): add GPU-utilization and cache-efficiency figures (rebut critic)
Two figures inserted into V2_DEEP_ANALYSIS §4.5 and §4.4 respectively, to
visually rebut the two critic-agent claims that we argued in prose were
design intent, not deficiencies.

(1) gpu_utilization.png  -- §4.5  "P GPU is wasted 90% of the time"
  Two-panel side-by-side:
    Left  (request count view, the naive reading): KVC P = 328 reqs (7.4%),
          KVC D = ~1450 each, DP = ~1100 each. P "looks idle."
    Right (compute work view, the honest reading): KVC P does 1.07M tokens
          of prefill, comparable to each KVC D worker's ~0.80M. P is a
          low-frequency high-cost safety net, not idle capacity.
  Bonus finding: KVC's total compute (3.47M tokens across 4 GPUs) is 33%
  LESS than DP's (5.17M). Same GPUs, less work done. That's the affinity
  win.

(2) cache_efficiency.png  -- §4.4  "Cache concentration is not policy win"
  Two-panel side-by-side. The setup: KVC has 27% LESS total KV pool
  (276K vs 351K tokens) yet caches MORE per request.
    Left  (cache hit rate vs turn number): KVC's session-affinity lets
          hit rate accumulate with turns; DP's hash + radix-LRU causes
          a mid-turn drift around turns 8-25 where KVC = 97.0% vs DP
          = 95.8% (1.24pp gap). Shows mechanism, not just outcome.
    Right (ECDF of per-request uncached tokens, log x): KVC's distribution
          concentrates near zero (50% < 187 tokens), DP's is spread
          (50% < 781 tokens). At uncached = 500 tokens threshold, KVC
          has 74% of requests below, DP has 31%.
  → smaller pool, better retention, less per-request work. Direct empirical
  rebuttal to "fragmentation is architectural, not policy."

Bundled scripts (rerunable):
- scripts/analysis/plot_gpu_utilization.py
- scripts/analysis/plot_cache_efficiency.py

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 18:04:49 +08:00
kzlin
c5519066de docs(kvc): add TTFT probability density figure (KVC v2 vs 4DP)
Adds a two-panel TTFT PDF comparison plot inserted as a new V2_DEEP_ANALYSIS
§3.4 ("TTFT 概率密度对比: bimodal vs unimodal"). Single-percentile numbers
(p50 / p99) hide the qualitative difference between the two distributions;
the figure makes it visible at a glance.

Left panel (linear x in [0, 0.6]s, body):
  KVC has a sharp peak at ~40ms (the direct-to-D fast path).
  DP has a broad peak around 50-200ms (full prefill per request).
  Annotated with p50 and p90 markers for each side.

Right panel (log x in [10ms, 10s], full range):
  KVC is visibly bimodal: a tall fast-path peak plus a small reseed tail
  around 1-5s.
  DP is unimodal: a single broad peak with shorter tail.
  Annotated with p99 callouts pointing to each tail.

KDE: scipy.stats.gaussian_kde, bandwidth=0.15 for the body (Scott's rule
oversmooths the sharp fast-path peak), log10-transformed for the full-range
panel so the bimodal structure is visible.

Bundled:
- scripts/analysis/plot_ttft_pdf.py -- rerunable when v2 / DP data change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 17:46:27 +08:00
kzlin
b5af19583b docs(kvc): replace v2 path breakdown tables with generated figures
V2_DEEP_ANALYSIS §3.1 (execution_mode distribution) and §3.2 (path-level
latency vs DP) had hand-typed tables with approximate latencies (e.g.
"~1.0s") and required readers to mentally compare 5+ rows × 5 columns.
Both sections now reference generated PNG figures derived directly from
the v2 + DP metrics.jsonl files.

§3.1 figure (v2_execution_mode_distribution.png):
  Horizontal bar chart, log x-axis. 4076 direct-to-D fast-path requests
  (green) dwarf the rest by ~30x; the long tail of slow / fallback /
  failure modes is visible at one glance. Counts and percentages
  annotated on each bar.

§3.2 figure (v2_path_level_latency.png):
  Grouped bar chart, log y-axis. Per-path TTFT p50 / TTFT p99 / Lat p50
  with exact numeric labels (no more "~1.0s" approximations). Sample
  counts annotated below each path. Quick visual reads:
   - KVC fast path TTFT p50 41ms vs DP 92ms (2.2x faster)
   - KVC reseed TTFT p99 5.12s vs DP 0.43s (12x slower) -- the cost
   - KVC no-d-capacity TTFT p99 7.65s (worst case)

Bundled:
- scripts/analysis/plot_v2_path_breakdown.py -- the script that
  generates both figures; rerunable when v2 data changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 17:38:43 +08:00
kzlin
37e9caa431 docs(kvc): production-decision reframe + formal router algorithm spec
After the critic-agent audit, V2_DEEP_ANALYSIS had drifted into an
audit-grade "5 wins / 1 loss / 3 draws" framing that mistook KVC's
deliberate design motifs (cache concentration via session affinity;
prefill-GPU idle as TTFT-stability trade-off) for "comparison
unfairness." This commit corrects the framing back to a production-
decision lens and adds a paper-track formal specification of the
router algorithm.

V2_DEEP_ANALYSIS_ZH.md changes:
- §0 TL;DR: lead with "online coding agent serving should pick
  KVC 1P3D"; the only real cost is TTFT p99 long-tail (3x DP) from
  the 8.3% mooncake reseed path, mitigable with real RDMA.
- §4 restructured into three buckets:
    real costs (TTFT p99 tail, abort accounting now fixed),
    counter-arguments to the critic (cache concentration and idle
      prefill GPU are design intent, not deficits),
    methodology to-do (naive-1P3D control, v2 N>=2 determinism).
- §6 replaces "5/1/3 rescoring" with production decision rationale:
  KVC wins on 6 latency/TTFT metrics + lower failure rate; pays
  TTFT p99 tail; lists workloads where DP would reverse the call.
- §8 decision points: D1 recommends Yes (accept v2 as milestone);
  D8 added: paper motif "KVC trades P idle for TTFT stability."

KVC_ROUTER_ALGORITHM.md (new, paper-track, Chinese narrative + English
algorithm boxes / variable names / theorems for direct paper reuse):
- Problem formulation, system model, full notation
- Algorithm 1 Route: lexicographic-tuple scoring on
    (overlap+alpha*sticky, sticky, -inflight, -assigned)
- Algorithm 2 Admit: D-worker autonomous admission deciding
    Direct / Seed / Reseed / reject (with reason)
- Algorithm 3 Dispatch: end-to-end orchestration with reset-on-success
    (the v2-specific fix that eliminates v1's self-amplifying thrashing)
- Theorem 1 (no permanent starvation) and Theorem 2 (fast-path
    determinism), each with a proof sketch
- Comparison table vs vanilla pd-disagg / DP cache-aware
- Anti-patterns ("what KVC explicitly is NOT")
- Open questions for reviewers
- Suggested paper citation phrasing
- Appendix A: algorithm-step to source-file:line crosswalk

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 17:29:18 +08:00
kzlin
0c25168cad docs(kvc): v2 deep analysis vs TEAM_REPORT baseline
Post-v2 audit consolidating ts=1 validation + v1 thrashing + v2 win, plus
critic-agent adversarial review of the v2 vs 4DP comparison.

Headline outcomes:
- TEAM_REPORT §1 (session pin starvation) fully fixed by v2 migration +
  reset-on-success; direct-to-D 42.8% -> 91.6%.
- TEAM_REPORT §2/§3/§5 (LRU, backpressure, admission RPC) are absorbed by
  ts=1 natural drain time, not mechanism-fixed -- will resurface under
  ts=10/longer traces/higher concurrency.
- TEAM_REPORT §6 (ts=10 distortion) confirmed and locked as precondition;
  TEAM_REPORT §8 (N=1 unreliable) rewritten to "high-pressure N>=3, normal N=1".

Three new problems exposed by adversarial review:
- TTFT p99: KVC 1.285s vs DP 0.427s (KVC 3.0x worse) -- cherry-picked out of
  the V2_RESULTS_ZH.md headline table. Root cause: 8.3% non-direct path pays
  3-7s mooncake reseed cost on 50-90K-token KV transfer.
- Error accounting asymmetry: DP has 67 fast-aborts (not 5) at ~0.08s each
  counted in latency stats; KVC's 5 ReadTimeouts excluded entirely. Root
  cause: --max-input-len 87811 (DP) vs 92098 (KVC) + metrics.py:124 filter.
- Topology mismatch: KVC 1P3D's prefill GPU is idle 91.7% of the time
  (only ~373/4449 requests use seed/P path); 4DP CA has all 4 GPUs at full
  utilization. Plus: no naive 1P3D control exists in the repo -- cannot
  isolate KVC-layer contribution from 1P3D-topology contribution.

Re-scored headline: 5 KVC wins / 1 DP win / 3 draws -- still net positive
but not the "7/8 wins" framing the V2_RESULTS_ZH.md claims.

Recommended follow-ups (ROI order):
1. naive 1P3D ts=1 N=1 control (critic's only CRITICAL finding)
2. v2 N=2/N=3 to verify ts=1 determinism with new code paths
3. symmetric error accounting recompute + DP max-input-len = 92098 rerun

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-11 11:17:00 +08:00