gahow/xserv
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
97 Commits 1 Branch 10 Tags
013465fc06490ca0b2a9fb821dbb47ac72ba22e7
Commit Graph

7 Commits

Author SHA1 Message Date
Gahow Wang
4088f49b7d cuda: infrastructure for whole-step CUDA graph capture 
- Thread-local launch stream (xserv_cuda::stream): every kernel
  wrapper, cublasSetStream, and NCCL collective now launches on
  current_stream_raw() — the legacy null stream by default (behavior
  unchanged), or the capture stream installed via push_stream during
  graph capture. Capture is impossible on the legacy stream.
- Allocator retain mode: blocks freed inside a retain window are
  quarantined (RetainedBlocks) instead of pooled, so an instantiated
  graph keeps exclusive ownership of every intermediate buffer it
  references across replays.
- Capture mode GLOBAL -> THREAD_LOCAL: concurrent TP rank threads
  must not poison each other's captures with their own cudaMallocs.
- embedding_device_ids / rope_inplace_device_pos: variants reading
  token ids / positions from persistent device buffers, replacing the
  per-call host upload that a captured region cannot contain.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
 2026-06-12 20:12:37 +08:00
Gahow Wang
5343391dbd review cleanups: pp+gpt-oss guard, sparse GEMV asserts, warnings 
- --pp with gpt-oss now fails with a clear message instead of a
  cryptic missing-weight panic inside the Qwen3-only PP engine.
- Sparse GEMV wrappers assert K%16==0 (FP8) / K%32==0 (MXFP4) — the
  uint4-vectorized kernels would silently drop a tail otherwise.
- Document the topk_ids buffer holding i32 under an F32 dtype label
  (DType has no I32).
- Drop unused imports/locals and the cuBLASLt scale-mode constants
  orphaned by the strided-batched FP8 rework (e631a71).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
 2026-06-12 17:02:59 +08:00
Gahow Wang
4c3f914459 kernels/cuda: paged-attention kernel, dispatch, pinned host memory 
CUDA layer for the paged-KV + swap work:
- csrc: new paged_attention.cu plus updates across attention/gemm/norm/
  activation/embedding/reduce kernels and common.cuh.
- xserv-kernels: new dispatch module and kernel-binding updates.
- xserv-cuda: cudaMallocHost/FreeHost bindings + PinnedBuffer (host swap
  pool backing) and offset-aware D2H/H2D copies used to move KV blocks
  between the GPU pool and pinned host memory.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
 2026-05-28 19:58:36 +08:00
Gahow Wang
986a289616 fix: 12 bug fixes from comprehensive review — 51 tok/s verified on RTX 5090 
P0 fixes (blocking usability):
- FIX-01: thread-local cuBLAS handle (was creating/destroying per matmul)
- FIX-16: EOS token no longer leaks into API responses
- FIX-17: max_seq_len configurable via --max-seq-len (default 2048, was hardcoded 256)
- FIX-18: max_tokens clamped to available seq space, prompt overflow returns 400

P1 fixes (bugs & performance):
- FIX-07: CachingAllocator wired into all hot paths (to_device, embedding, rope, concat)
- FIX-08: CudaDeviceProp buffer increased to 32KB for CUDA 12.9 safety
- FIX-09: tokenizer byte_fallback graceful degradation (was panic)
- FIX-19: causal mask uses -INFINITY instead of -1e9 (BF16 supports inf)
- FIX-20: LayerNorm rewritten to numerically stable two-pass algorithm
- FIX-21: min block size guard (32 threads) for LayerNorm/RMSNorm launches

P2 fixes (improvements):
- FIX-22: Option<GpuKVCache> + take() eliminates dummy KV cache allocations
- FIX-23: RoPE cache no longer artificially capped at 8192 positions

Verified on dash5 (RTX 5090): 51 tok/s batch=1, 74 tok/s 2-concurrent, 1.7-3.3x HF transformers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
 2026-05-23 14:13:43 +08:00
Gahow Wang
d5532ef209 phase 15: Tensor::empty + CUDA Graph infra — 50.3 tok/s (140% of HF, 45% roofline) 
Two optimizations:

1. Tensor::empty() — skip cudaMemset for output tensors
   All kernel wrappers that fully overwrite their output now use
   Tensor::empty() instead of Tensor::zeros(). Eliminates ~756
   cudaMemset calls per decode step (21 per layer × 36 layers).
   Improvement: 46.6 → 50.3 tok/s (+8%).

2. CUDA Graph infrastructure (for future use)
   Added FFI bindings (cudaStreamBeginCapture, cudaGraphInstantiate,
   cudaGraphLaunch) and RAII CudaGraph wrapper. Not yet used in the
   forward pass due to variable kv_len, but provides foundation for
   future graph-based decode optimization.

Ablation (dash5, RTX 5090, Qwen3-8B BF16, serial decode):

| Optimization | tok/s | vs HF | Roofline |
|-------------|-------|-------|----------|
| Phase 14 baseline | 12.9 | 36% | 12% |
| + Fused kernels | 13.2 | 37% | 12% |
| + Batched decode | 13.2 (serial) | 37% | 12% |
| + Custom GEMV | 46.6 | 130% | 42% |
| + Tensor::empty | 50.3 | 140% | 45% |

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
 2026-05-22 23:57:34 +08:00
Gahow Wang
ee68d3565d fix: comprehensive review + 14 bug fixes + Phase 12/14 overhaul 
Strict code review identified 30+ issues across correctness, performance,
and architecture. This commit addresses 14 of them with verified fixes,
restructures Phase 12 for honest continuous batching, and updates Phase 14
to target FA2 (RTX 5090 SM120 lacks TMEM required by FA4).

Bug fixes:
- FIX-01: Global cuBLAS handle (thread-local singleton, was per-call)
- FIX-02: Remove 19 unnecessary cudaDeviceSynchronize calls from kernels
- FIX-03: Qwen3 ChatML template (was plain text concatenation)
- FIX-04: EOS token from tokenizer (was hardcoded 151645)
- FIX-05: Storage tracks actual GPU device ordinal (was always Cuda(0))
- FIX-06: unsqueeze stride preserves contiguous layout
- FIX-08: CudaDeviceProp replaced with heap buffer (was UB-prone padding)
- FIX-09: Tokenizer byte_fallback to <0xNN> tokens (was panic)

Feature additions:
- FIX-10: SSE streaming (/v1/chat/completions, OpenAI-compatible)
- FIX-11: Correct usage statistics (prompt/completion/total tokens)
- FIX-13: Temperature / top-k / top-p sampling with SamplingParams

Performance improvements:
- FIX-07: Caching allocator wired up (thread-local pool, pooled flag)
- FIX-12: KV cache staging buffers (zero-alloc get_kv_len via borrow_raw)
- FIX-14: GPU strided copy kernel (eliminates contiguous() CPU round-trip)

Architecture:
- Phase 12 engine restructured: prefill/decode separation, honest TODO
  for batched GPU forward (requires Flash Attention)
- Phase 14 updated: FA2 for SM120 (FA4 requires TMEM, absent on 5090)
- Qwen3-7B → Qwen3-8B typo fixed across all docs (36 layers, hidden 4096)

Validated on dash5 (8x RTX 5090):
- 52/52 API prompts pass (EN/CN/code), SSE streaming verified
- Logits match HF transformers 9/10 top-1, 4.0/5 avg top-5 overlap
- 8 concurrent requests: 5.99x scheduling speedup (batch_size=4)
- Throughput: 10.3 tok/s (serial), 30% of HF baseline

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
 2026-05-22 17:53:28 +08:00
Gahow Wang
c8e8153702 phase 4: transformer core kernels 
CUDA kernels (csrc/):
- common.cuh: shared warp_reduce_sum/max, block_reduce_sum/max
- normalization/rmsnorm.cu: RMSNorm (F32 + BF16)
- normalization/layernorm.cu: LayerNorm with Welford (F32 + BF16)
- activation/activations.cu: GELU tanh-approx + SiLU (F32 + BF16)
- reduce/softmax.cu: safe softmax, 3-pass (F32 + BF16)
- embedding/embedding.cu: gather lookup (F32 + BF16)
- embedding/rope.cu: RoPE in-place + precomputed cos/sin cache (F32 + BF16)

Rust wrappers (xserv-kernels/src/):
- rmsnorm.rs, layernorm.rs, activation.rs, softmax.rs, embedding.rs, rope.rs
- RopeCache struct with GPU-side precomputation

Tests: 12 new tests (ops_test.rs), all passing with good precision:
- F32: max_err 1e-6 ~ 1e-9
- BF16: max_err 2e-3 ~ 7e-3
Total: 29 kernel tests + 27 prior = 56 tests passing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
 2026-05-21 21:07:24 +08:00