Files
el/lang/runtime/eg_cosine_batch.h
T
bigmerge b3f410fc91
El SDK CI - dev / build-and-test (pull_request) Failing after 4m29s
engram: batch-cosine Adapter/Strategy/Factory over ggml, supersedes hand-rolled PR #114
Stop hand-rolling GPU kernels for batch cosine similarity — use ggml (the
MIT-licensed compute library underneath llama.cpp, installed standalone via
Homebrew) as the preferred backend, without ripping out PR #114's
carefully-verified hand-rolled Metal shader.

Structure: one stable public adapter (eg_cosine_batch.h, zero #ifdef at call
sites) backed by three selectable concrete Strategies behind an internal
vtable (eg_cosine_batch_strategy.h) chosen by a Factory (eg_cosine_batch.c):

  - eg_cosine_batch_strategy_ggml.c    — NEW. ggml + dynamically-loaded Metal
                                          backend plugin (ggml_backend_load_all_from_path
                                          + ggml_mul_mat for the batched dot
                                          product), gather/scatter around the
                                          -2.0 sentinel contract.
  - eg_cosine_batch_strategy_metal_hand.m — PR #114's original hand-rolled
                                          Metal shader bridge, preserved
                                          almost verbatim, now one strategy
                                          among several rather than the only
                                          option. eg_cosine_batch.metal kept
                                          byte-identical to the original.
  - eg_cosine_batch_strategy_cpu.c     — universal always-false fallback
                                          (direct descendant of PR #114's
                                          eg_metal_cosine_stub.c).

Selection: EL_COSINE_BATCH_STRATEGY=ggml|metal|cpu|auto (default: ggml first,
then hand-rolled Metal, then CPU — first available wins), plus back-compat
EL_METAL_COSINE=0 to disable every GPU-backed strategy. build_vindex_bench.sh
compiles all three strategies on Darwin, CPU-fallback-only elsewhere.

vindex_bench.c now reports BRUTE-GGML and BRUTE-METAL side by side against
the same CPU oracle, on the same dataset, in one run (real numbers vs. real
store snapshot in the PR body).
2026-08-15 17:16:41 -05:00

107 lines
5.5 KiB
C

/* eg_cosine_batch.h — stable Adapter interface over batch-cosine-similarity
* BACKEND STRATEGIES. This header is the ONE thing call sites (el_runtime.c,
* vindex_bench.c, ...) talk to. Plain C11, safe to #include on every
* platform — the symbols declared here always exist and always link,
* regardless of what backend actually runs underneath. Zero #ifdef at call
* sites: which concrete strategy executes (ggml/Metal, hand-rolled Metal, or
* the always-false CPU fallback) is resolved once, lazily, inside
* eg_cosine_batch.c's factory — see eg_cosine_batch_strategy.h for that.
*
* This supersedes eg_metal_cosine.h (PR #114's single hand-rolled-Metal-only
* bridge). The contract is UNCHANGED — same shapes, same sentinel, same
* never-partial guarantee, same "caller must always be prepared to fall back
* to its own scalar per-node loop" rule — only the name changed, because the
* thing behind it is no longer "the Metal bridge," it is "whichever batch-
* cosine strategy the factory picked." eg_metal_cosine.h's original doc
* comments (byte-for-byte, this file is the direct descendant) are preserved
* below since they remain the precise spec any strategy must honor.
*
* On ANY failure at ANY step — no compute device, compile/init error, alloc
* failure, bad args — every function here returns false and writes nothing.
* Out-params are either fully populated or left completely untouched, never
* partial. Callers MUST always be prepared to fall back to their own scalar
* per-node CPU loop unconditionally. These functions must never crash, throw,
* or hang the calling process — several call sites run inside a long-lived
* daemon's request-handling hot path.
*/
#ifndef EG_COSINE_BATCH_H
#define EG_COSINE_BATCH_H
#include <stdint.h>
#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Batched cosine similarity: one query vector against `n` node vectors.
*
* query — qdim floats, the query embedding. Raw/unnormalized.
* qdim — query dimensionality (e.g. 768 for nomic-embed-text).
* node_ptrs — array of n pointers, node_ptrs[i] pointing at a (possibly
* differently-owned, possibly NULL) float vector for node i.
* NOT required to be contiguous — every strategy performs the
* gather into a packed row-major matrix internally, exactly
* mirroring how EngramNode.emb is one malloc per node.
* node_dims — array of n ints, node_dims[i] = that node's real emb_dim
* (0 or mismatched vs qdim => that node scores -2.0, matching
* eg_cosine's null/dim-mismatch/zero-norm sentinel exactly).
* n — number of nodes.
* out_scores — caller-owned array of n doubles; out_scores[i] is filled
* with the cosine similarity of node i against query, or
* -2.0 for a null/dim-mismatched/zero-norm node — bit-for-bit
* the same contract as eg_cosine(node_ptrs[i], query, qdim).
*
* Returns true iff a real backend strategy ran and out_scores was fully
* populated. Returns false (out_scores left untouched) on ANY failure or
* unavailability — no compute device, compile/init failure, allocation
* failure, n<=0, qdim<=0, null query/node_ptrs/node_dims/out_scores.
*/
bool eg_cosine_batch(const float* query, int32_t qdim,
const float* const* node_ptrs,
const int32_t* node_dims,
int32_t n,
double* out_scores);
/* True iff a real (non-CPU-fallback) strategy is available right now (cheap
* after the first call — cached). Purely informational (e.g. a startup log
* line or /api/stats field); callers should still treat a false return from
* eg_cosine_batch()/eg_cosine_batch_multi() itself as the authoritative
* fallback signal, not this function. */
bool eg_cosine_batch_available(void);
/* Which concrete strategy is currently selected — "ggml", "metal-hand",
* or "cpu-fallback". Purely informational/diagnostic, same spirit as
* eg_cosine_batch_available(). Never NULL. */
const char* eg_cosine_batch_strategy_name(void);
/* Multi-query batched cosine: nq query vectors against the SAME n node
* vectors, in one call. A real strategy uploads/prepares the node population
* ONCE and reuses it for every query, instead of nq separate
* eg_cosine_batch() calls each paying the full gather+upload cost — PR #114
* measured this necessary: at N~=13.7k/dim=768, repeating the single-query
* call per query was slower than the CPU baseline; batching queries together
* is what makes a GPU-backed path a real win at this shape. Use this
* whenever multiple queries will run against an unchanged (or
* rarely-changing) node population; use eg_cosine_batch() for a genuinely
* one-off comparison.
*
* queries — nq*qdim floats, row-major (query i at queries+i*qdim).
* out_scores — caller-owned nq*n doubles, row-major
* (out_scores[i*n+j] = cosine(queries[i], node j)), same
* -2.0 sentinel semantics as eg_cosine_batch().
*
* Returns true iff a real strategy ran and out_scores was fully populated
* (all nq*n entries); false (untouched) on any failure/unavailability. */
bool eg_cosine_batch_multi(const float* queries, int32_t qdim, int32_t nq,
const float* const* node_ptrs,
const int32_t* node_dims,
int32_t n,
double* out_scores);
#ifdef __cplusplus
}
#endif
#endif /* EG_COSINE_BATCH_H */