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LocalAI/backend/cpp/ds4/Makefile
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Claudio Maradonna 9e831d7709 fix(ds4): build CUDA kernels for the target architecture (#11840)
* fix(ds4): build CUDA kernels for the target architecture

The ds4 backend compiled its CUDA objects with no -arch. Upstream's Makefile
leaves CUDA_ARCH empty and its `cuda` target refuses to build without one,
offering `cuda-spark` (sm_121) and `cuda-generic` (native) instead. We invoke
its object targets directly, which bypasses that guard, so nvcc fell back to
its default architecture and the kernels ran as JIT'd PTX on the real GPU.

On GB10 (sm_121) that silently corrupted inference: any prompt over roughly 128
tokens produced text unrelated to the input and never closed its thinking
block, so content came back empty and the chat showed only reasoning; longer
prompts failed with "cuda decode failed". It also cost close to two orders of
magnitude of prefill throughput. Measured on one box, same model, same prompt,
same GPU, upstream ds4 at the pinned commit, differing only in the nvcc flags:

  make -B ds4      (archless, as we build it)   garbage output    4.21 t/s
  make cuda-spark  (compute_121a/sm_121a)       correct output  325.70 t/s

Select an architecture list from CUDA_MAJOR_VERSION, which the backend matrix
already declares for both ds4 cublas entries but Dockerfile.ds4 never forwarded.
Upstream's CUDA_ARCH takes a single value, so it cannot express the fat binary
these images need; NVCC_ARCH_FLAGS is overridden instead, since a command-line
assignment wins over its `:=`. The lists are copied from vllm-cpp rather than
invented so the two CUDA images cover the same GPUs, with l4t/arm64 covering
Orin, Thor and GB10. An empty CUDA_MAJOR_VERSION keeps upstream's `native`
behaviour for local developer builds, and no CI runner has a GPU to enumerate.

DS4_CUDA_HAVE_MXF4 is deliberately left unset: upstream defines it only for
single-arch sm_120/sm_121 builds and guards it with a plain #ifdef rather than
__CUDA_ARCH__, so it cannot be combined with older archs. It gates an optional
MXFP4 indexer fast path whose #ifndef branch returns 0 and falls back cleanly,
so omitting it costs speed on GB10, not correctness.

Assisted-by: Claude Code:claude-opus-5
Signed-off-by: Claudio Maradonna <git@codeshifter.xyz>

* test(ds4): cover the multi-batch prefill regression

The architecture fix has no automated guard: every existing e2e spec uses a
short prompt, and the miscompiled backend answered short prompts correctly.
The corruption only appears once a prompt spans more than one prefill batch,
so the whole suite passed against a backend that produced garbage in normal
use.

Add an opt-in "long_prefill" capability to the backend e2e suite that sends a
prompt well past one batch with a known needle and asserts the answer still
reflects it, and document in the ds4 guide why the build must never omit an
nvcc architecture, how to check which flags a configuration resolves to
without compiling, and how to run the new spec.

Assisted-by: Claude Code:claude-opus-5
Signed-off-by: Claudio Maradonna <git@codeshifter.xyz>

---------

Signed-off-by: Claudio Maradonna <git@codeshifter.xyz>
2026-09-03 13:03:44 +02:00

146 lines
6.3 KiB
Makefile

# ds4 backend Makefile.
#
# Upstream pin lives below as DS4_VERSION?=8db89fe083ae4d17c9a2428ccd29803d3ae8f577
# (.github/bump_deps.sh) can find and update it - matches the
# llama-cpp / ik-llama-cpp / turboquant convention.
DS4_VERSION?=8db89fe083ae4d17c9a2428ccd29803d3ae8f577
DS4_REPO?=https://github.com/antirez/ds4
CURRENT_MAKEFILE_DIR := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
BUILD_DIR := build
BUILD_TYPE ?=
NATIVE ?= false
JOBS ?= $(shell nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || echo 4)
UNAME_S := $(shell uname -s)
CMAKE_ARGS ?= -DCMAKE_BUILD_TYPE=Release
# nvcc must be told the target architecture explicitly for a cublas build, and
# this is not a tuning knob. Upstream's Makefile leaves CUDA_ARCH empty and its
# `cuda` target REFUSES to build without one, offering `cuda-spark`
# (CUDA_ARCH=sm_121) and `cuda-generic` (CUDA_ARCH=native) instead. We drive its
# object targets directly, which bypasses that guard: nvcc then compiles with no
# -arch at all, and the kernels run as JIT'd PTX for its default architecture.
# On GB10 (sm_121) that silently produced corrupt inference output above a
# ~128-token prefill batch and ~77x slower prefill (4.21 t/s vs 325.70 t/s,
# measured on the same box with the same model). No CI runner has a GPU, so
# `native` has nothing to enumerate there.
#
# Upstream's CUDA_ARCH takes a SINGLE value (see its sm_120/sm_121 special cases
# and the `-arch=$(CUDA_ARCH)` fallback), so it cannot express the fat binary
# these images need. NVCC_ARCH_FLAGS is overridden instead: a command-line
# assignment wins over the `:=` in upstream's Makefile, and its NVCCFLAGS
# expands whatever we pass.
#
# The architecture lists are copied from backend/go/vllm-cpp/Makefile rather
# than invented, so the two CUDA images cover the same GPUs: amd64 datacenter +
# consumer, and l4t/arm64 covering Orin (87), Thor (110) and GB10 (121a).
#
# -DDS4_CUDA_HAVE_MXF4=1 is deliberately NOT set. Upstream only defines it for
# single-arch sm_120/sm_121 builds and guards the code with a plain #ifdef
# rather than __CUDA_ARCH__, so it cannot be combined with older archs in one
# fat binary. It gates an optional MXFP4 indexer fast path whose #ifndef branch
# returns 0 and falls back to the generic path, so omitting it costs some speed
# on GB10, not correctness. Revisit if upstream adds __CUDA_ARCH__ guards.
#
# An EMPTY CUDA_MAJOR_VERSION means a local developer build, not CI: fall back
# to upstream's own `native` handling, which needs a GPU present but is what a
# developer building on their own machine wants. Both variables are `?=` so an
# explicit value on the command line always wins.
UNAME_M := $(shell uname -m)
CUDA_MAJOR_VERSION ?=
ifeq ($(BUILD_TYPE),cublas)
ifeq ($(CUDA_MAJOR_VERSION),13)
ifeq ($(UNAME_M),aarch64)
DS4_NVCC_ARCH_FLAGS ?= -gencode arch=compute_87,code=sm_87 \
-gencode arch=compute_90a,code=sm_90a \
-gencode arch=compute_100a,code=sm_100a \
-gencode arch=compute_110,code=sm_110 \
-gencode arch=compute_121a,code=sm_121a
else
DS4_NVCC_ARCH_FLAGS ?= -gencode arch=compute_80,code=sm_80 \
-gencode arch=compute_86,code=sm_86 \
-gencode arch=compute_89,code=sm_89 \
-gencode arch=compute_90a,code=sm_90a \
-gencode arch=compute_100a,code=sm_100a \
-gencode arch=compute_103a,code=sm_103a \
-gencode arch=compute_120a,code=sm_120a \
-gencode arch=compute_121a,code=sm_121a
endif
DS4_ARCH_MAKEVARS := NVCC_ARCH_FLAGS="$(DS4_NVCC_ARCH_FLAGS)"
else ifeq ($(CUDA_MAJOR_VERSION),)
# Local build: let upstream resolve the host GPU.
DS4_ARCH_MAKEVARS := CUDA_ARCH=native
else
$(error CUDA_MAJOR_VERSION=$(CUDA_MAJOR_VERSION) has no architecture list here (13 does). Leave it empty for a native build, or pass DS4_NVCC_ARCH_FLAGS explicitly.)
endif
endif
# Upstream splits distributed inference, tensor-parallel transport, the SSD
# expert cache, and layer placement into GPU-agnostic translation units. They
# are shared by every GPU mode, so append them unconditionally below.
ifeq ($(BUILD_TYPE),cublas)
CMAKE_ARGS += -DDS4_GPU=cuda
DS4_OBJ_TARGET := ds4.o ds4_cuda.o ds4_distributed.o ds4_tp.o ds4_ssd.o ds4_layer_pack.o \
cuda/mmq/ds4_ggml_stubs.o cuda/mmq/ds4_mmq.o cuda/mmq/ds4_mmq_d2r.o \
cuda/mmq/quantize.o cuda/mmq/mmid.o cuda/mmq/mmvq.o cuda/mmq/ds4_repack.o
else ifeq ($(UNAME_S),Darwin)
CMAKE_ARGS += -DDS4_GPU=metal
DS4_OBJ_TARGET := ds4.o ds4_metal.o ds4_distributed.o ds4_tp.o ds4_ssd.o ds4_layer_pack.o
else
# CPU reference path (Linux only - macOS CPU path is broken by VM bug per ds4 README).
CMAKE_ARGS += -DDS4_GPU=cpu
DS4_OBJ_TARGET := ds4_cpu.o ds4_distributed.o ds4_tp.o ds4_ssd.o ds4_layer_pack.o
endif
ifneq ($(NATIVE),true)
CMAKE_ARGS += -DDS4_NATIVE=OFF
endif
.PHONY: grpc-server package clean purge test all
all: grpc-server
# Clone the upstream ds4 source at the pinned commit. Directory acts as the
# target so make only re-clones when missing. After a DS4_VERSION bump,
# run 'make purge && make' to refetch (or rely on CI's clean build).
ds4:
mkdir -p ds4
cd ds4 && \
git init -q && \
git remote add origin $(DS4_REPO) && \
git fetch --depth 1 origin $(DS4_VERSION) && \
git checkout FETCH_HEAD
# Build ds4's engine object files via its own Makefile, which already encodes
# the right per-platform compile flags (Objective-C/Metal on Darwin, nvcc on Linux+CUDA).
ds4/ds4.o: ds4
ifeq ($(BUILD_TYPE),cublas)
+$(MAKE) -C ds4 $(DS4_ARCH_MAKEVARS) $(DS4_OBJ_TARGET)
else ifeq ($(UNAME_S),Darwin)
+$(MAKE) -C ds4 ds4.o ds4_metal.o ds4_distributed.o ds4_tp.o ds4_ssd.o ds4_layer_pack.o
else
+$(MAKE) -C ds4 ds4_cpu.o ds4_distributed.o ds4_tp.o ds4_ssd.o ds4_layer_pack.o
endif
grpc-server: ds4/ds4.o
mkdir -p $(BUILD_DIR)
cd $(BUILD_DIR) && cmake $(CMAKE_ARGS) $(CURRENT_MAKEFILE_DIR) && cmake --build . --config Release -j $(JOBS)
cp $(BUILD_DIR)/grpc-server grpc-server
cp $(BUILD_DIR)/ds4-worker ds4-worker
package: grpc-server
bash package.sh
test:
@echo "ds4 backend: e2e coverage at tests/e2e-backends/ (BACKEND_BINARY mode)"
clean:
rm -rf $(BUILD_DIR) grpc-server ds4-worker package
if [ -d ds4 ]; then $(MAKE) -C ds4 clean; fi
purge: clean
rm -rf ds4