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[Spec Decode] RecoverSSM: commit all GDN KV cache groups with one set of launches - #61017
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RecoverSSM's commit-plan and conv-window compaction kernels are model independent. Move them from models/kimi_k3 into model_executor/layers/mamba/ops/recoverssm.py (Kimi-K3 keeps its private names as import aliases; kernel source unchanged), add mamba/recoverssm_utils.py (activation predicate, argument validation) and the generic spec-row/request mapping helpers to v1/attention/backends/recoverssm_metadata.py. CacheConfig.use_kda_recoverssm becomes use_recoverssm: the switch now selects RecoverSSM for any model whose recurrent layers implement it, not only KDA. No functional change for Kimi-K3. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
With --use-replayssm and speculative decoding, Qwen4Exp's Gated DeltaNet layers verify the draft window from a read-only checkpoint and keep a per-token replay record [correction(V), normalized key(K), gate(1)] in fp32. After sampling, one commit replays the accepted tokens and writes the recurrent state once (plus the block-boundary state in align mode), instead of snapshotting the state after every draft position. The PLE dilated short conv follows the same protocol (accepted-suffix compaction). num_speculative_blocks = 0, so no per-draft Mamba blocks are reserved. - GDN verify/commit kernels: model_executor/layers/mamba/gdn/recoverssm_gdn.py - metadata/backends: v1/attention/backends/gdn_recoverssm.py, ple_recoverssm.py - the verify reads strided q/k/v views of the conv output and writes in place - builders declare AttentionCGSupport.NEVER: FULL_AND_PIECEWISE falls back to PIECEWISE; the fallback now also counts breakable CUDA graphs (empty splitting_ops, with or without torch.compile) as piecewise attention instead of dropping to NONE - the generic Mamba metadata builder skips the Mamba2 ReplaySSM ring-buffer workspaces when --use-replayssm selects RecoverSSM (the PLE short conv uses that builder) - tests: GDN verify/commit vs the native kernels (fp32 and bf16 state, align boundaries, mixed and ragged batches, extreme gates), PLE vs token-by-token decode, config selection Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
A speculative window whose accepted tokens end exactly on a recurrent block boundary selected the following block-table column for the committed state (commit plan) and recorded it as the running column (postprocess). That column can still be unallocated, so the next step reads an uninitialized page. Select the block that holds the last committed token, matching the (n - 1) // block convention used elsewhere in align mode. Applies to Kimi-K3 KDA and to the Qwen GDN/PLE RecoverSSM paths that share the plan. Fix and test from local-inference-lab/vllm a02f585 (Martin Vit, root cause reported by astra); the GDN/PLE align tests now expect the same convention. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Martin Vit <martin@voipmonitor.org> Co-authored-by: Claude <noreply@anthropic.com>
…rofiling Under PIECEWISE CUDA graphs, capture dummy runs are prepared with for_capture=False, so RecoverSSMState records their step. That step's metadata holds the commit contexts, which reference the profiling KV cache, and the profiling teardown did not drop it. The profiling KV cache then stayed allocated and the real KV cache allocation ran out of memory (Qwen3.8-Flash-Next with MTP3 and --use-replayssm: about 26 GiB held on H200 TP1). Reset the recorded step in the teardown. Signed-off-by: Zihua Wu <13583761+lucifer1004@users.noreply.github.com> Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
…rward_core One RecoverSSM check in QwenGatedDeltaNetAttention._forward_core read self.use_gdn_recoverssm directly while its neighbours use getattr with a False default. Layers built without __init__ (the fused MTP model-path tests' stand-ins) have no such attribute, so tests/kernels/mamba/test_gdn_fused_mtp.py failed with AttributeError. Signed-off-by: Zihua Wu <13583761+lucifer1004@users.noreply.github.com> Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
In align mode every program folded both the final state and the block-boundary state, keeping two [BV, BK] fp32 accumulators live for all rows although only windows that cross a block boundary store a boundary state. The doubled live tiles cut occupancy: on H200 the commit of 12 layers x 8 requests x 48 heads ran at 2.1 TB/s against 2.9 TB/s without align mode. Give align mode a second half on grid axis 0 whose programs fold only the boundary prefix and exit unless the window crosses a boundary, so every program keeps one tile live, and use 16-row tiles. The same commit now takes 197 us instead of 290 us (3.1 TB/s; a contiguous copy of the same traffic reaches 4.2 TB/s). At concurrency 8 on one H200 this removes about 0.27 ms of the 0.8 ms per-step commit. Signed-off-by: Zihua Wu <13583761+lucifer1004@users.noreply.github.com> Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
…decode batches The GDN and PLE RecoverSSM metadata builders declare UNIFORM_BATCH, so --use-replayssm resolves FULL_AND_PIECEWISE instead of falling back to PIECEWISE. Graph padding rows get a null state slot and a zero-length window, so the verify kernel writes nothing for them; a new test pads a batch and checks that no state changes. GB10 (TP1, Qwen3.8-Flash-Next NVFP4, MTP K=5, 2 starts per arm): FULL_AND_PIECEWISE vs PIECEWISE code c=1 -1.1..-2.1 % ms/tok, c=4 level, identical greedy text. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
…ndary states The one-fold-per-program commit ran the final-state and the boundary-state folds as programs of one launch. Both read the window's source state, and in align mode a boundary state can be written into that same slot: a crossing window's boundary state goes into its source block, and a window ending exactly on a boundary keeps its final state (equal to its boundary state) in that block. A program could then read a source tile another program had already overwritten. test_recoverssm_gdn.py failed in 9 of 12 runs on GB10 (0 of 12 with the previous fused kernel). The boundary folds now run as a second launch after the final folds, and skip windows whose boundary slot is their final slot. Every program still runs one fold. 0 of 20 runs fail; greedy output on Qwen3.8-Flash-Next is unchanged. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
Conflicts with main's Mamba2 ReplaySSM speculative decoding (FlashInfer): - config/vllm.py: main now sets the RecoverSSM flag per architecture (KDA models only) and routes every other speculative --use-replayssm model to Mamba2 ReplaySSM; the RecoverSSM architectures now include Qwen4Exp, and the Qwen4Exp check and main's FlashInfer buffer check both stay. - config/cache.py: main's docstring, this PR's field name (use_recoverssm). - mamba/abstract.py: main's use_replayssm (both paths skip the per-draft blocks). - tests/test_config.py: main's new case reads use_recoverssm. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
…ay, bit-identical to per-token The verify kernel now records the decay it multiplied by, exp(g), instead of g, and the commit replays the accepted tokens forward with the same update, h = fma(c, k, h * decay), instead of the backward closed form (sum of c k * decay, then s0 * decay + corr). The committed state is then the native per-token state bit for bit. Suggested by @ArtyomITA in the PR thread (with a server check on sm_120); same cost (n loads of c, k and the decay). tests/kernels/mamba/test_recoverssm_gdn.py: the FP32 commit, align-boundary and extreme-gate checks now require torch.equal against the native per-token states (5 assertions, 28 cases). On a GB10 the closed form fails 28 of them, this passes all 62; tests/config/test_recoverssm_config.py unchanged (18 passed). Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
vllm-project#58997 removed mamba_cache_mode "all" and rejects it in CacheConfig; test_config.py covers that now. Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com> Co-authored-by: Claude <noreply@anthropic.com>
# Conflicts: # vllm/model_executor/layers/mamba/gdn/qwen_gdn_linear_attn.py
…ess tables The GDN commit context and the PLE conv commit built their pointer tables with torch.tensor(..., dtype=torch.int64), which raises "Overflow when unpacking long long" for device pointers with the top bit set (XPU). Store the uint64 bit pattern in the int64 table, as vllm-project#48109 does for the Mamba state pointers; the kernels only cast the value back to a pointer, so nothing changes on CUDA. Reported with a fix by @TSUMUGI-XE on 2× Arc Pro B70. AI assistance (Claude Code) was used; the change was reviewed line by line. Co-authored-by: TSUMUGI-XE <291260587+TSUMUGI-XE@users.noreply.github.com> Co-authored-by: Claude <noreply@anthropic.com> Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com>
vllm/config/vllm.py: main removed ROCM_DEFAULT_MRV1_ARCHITECTURES (vllm-project#56360); keep only _QWEN4EXP_RECOVERSSM_ARCHS. tests/kernels/mamba/test_recoverssm_ple.py: ple_conv moved to vllm.models.qwen4_exp.common.ops.ple upstream (same signature). Co-authored-by: Claude <noreply@anthropic.com> Signed-off-by: Jürgen Schmied <juergenschmied70@gmail.com>
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… of launches commit_step committed each KV cache group on its own: for every group, a plan, a conv and a state launch (and the align update). A model whose GDN layers are split over several groups pays that host cost once per group. GDNRecoverSSMGroupedCommit merges the groups' layers into one commit context. Each layer records its group; the plan runs one program row per group and the conv and state kernels read the layer's group state indices (and block table in align mode) through per-group address tables, each group with its own slice of the plan. The shared kernels take the tables as optional arguments, so one group (and the PLE and KDA paths) launches as before. commit_step groups the GDN metadata when every group has spec rows with the same per-request inputs and falls back to the per-group loop otherwise. The align update writes the same values for every group, so it runs once. Co-authored-by: Claude <noreply@anthropic.com> Signed-off-by: tsumugi-xe <291260587+tsumugi-xe@users.noreply.github.com>
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Follow-up to #58863, as suggested there (#58863 (comment)). Stacked on #58863; only the last commit is new.
Purpose
commit_stepcommits each KV cache group on its own: for every group with GDN layers, a plan, a conv and a state launch (and the align update). When a model's GDN layers are split over several groups, that host cost is paid once per group, on the single-stream critical path after sampling.This adds
GDNRecoverSSMGroupedCommit, which merges the groups' layers into one commit context:[group, batch]copy of the state indices, the kernels read each group's existing tensor through a small address table: copying the groups' indices into one table would itself take one launch per group.prepare_commit_plan_kernel,compact_conv_state_kernel) take the tables as optional arguments. WithNonethey run as before, so one group, PLE and KDA launch exactly as now.commit_stepgroups the GDN metadata when every group has spec rows with the same per-request inputs (accepted counts, query offsets, request mapping, computed tokens, block size), and falls back to the per-group loop otherwise, or when the groups' layers cannot share one context.commit_stepstays where it is, outside graph capture.Test Result
New tests in
tests/kernels/mamba/test_recoverssm_gdn.py: three KV cache groups of two GDN layers each, spec rows 0, 2, 3 of a 5-request batch, each group with its own blocks; the grouped commit leaves every conv state and checkpoint bit for bit as one commit per group, without and with align mode, over two steps with new state-index tensors. Plus a test that mismatched groups are rejected.Run on XPU (2× Intel Arc Pro B70; one card; the CUDA-only tests run from a local copy with the device swapped): the new tests pass. The existing tests that compare the commit with the native per-token states bit for bit fail on XPU with and without this change (the same 28), so they don't say anything about this change there. The new tests compare the grouped commit with the per-group commit, not with the native kernel, so they don't depend on that comparison. Not run on CUDA.
Host time of the commit (XPU, one card, synthetic tensors, 3 KV cache groups × 6 GDN layers like one PP stage of Qwen3.8-Flash-Next):
Server (2× Arc Pro B70, Qwen3.8-Flash-Next, PP=2 with our follow-up [Spec Decode][Mamba] RecoverSSM: support pipeline parallelism (non-last ranks commit in the deferred PP postprocess) #59983, MTP K=1, on our own tree with the same change): we alternated between the per-group loop and the grouped commit inside one server process (a local-only switch, not part of this PR), because the decode slope of this setup moved between server starts by more than the expected gain (30.5 to 32.9 ms/token over four starts of the same configuration). Over 2 starts × 3 rounds, the grouped commit lowered the single-stream decode slope by 0.19 ms/token (31.39 → 31.20 ms/token; every one of the 6 rounds lower, by 0.19 to 0.22). Per-token logprobs stayed within our run-to-run noise against the Triton/FLA path without RecoverSSM, and MTP acceptance was 1.76 in both starts. The log confirmed both PP ranks took the grouped commit (3 KV cache groups, 18 GDN layers per PP rank).
ruff check/ruff formatpass on the changed files (one existing E501 inrecoverssm_gdn.pyis not from this change).Not tested: CUDA; this exact branch end to end (the server run used our tree, which also carries [Spec Decode][Mamba] RecoverSSM: support pipeline parallelism (non-last ranks commit in the deferred PP postprocess) #59983 and our XPU changes); the fallback to the per-group loop on a server (the unit tests cover only the rejection of mismatched groups); the KDA path with several groups (KDA keeps its own commit and only gets the new optional arguments).
Written with AI assistance (Claude Code); every changed line was reviewed by the submitter.
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