Add partitioning_avx2.cpp for PQFastScan

cmake/libs/libfaiss.cmake

@@ -10,6 +10,7 @@ knowhere_file_glob(GLOB FAISS_AVX2_SRCS
                    thirdparty/faiss/faiss/impl/*avx.cpp
                    thirdparty/faiss/faiss/impl/pq4_fast_scan_search_1.cpp
                    thirdparty/faiss/faiss/impl/pq4_fast_scan_search_qbs.cpp
+                   thirdparty/faiss/faiss/utils/partitioning_avx2.cpp
                    thirdparty/faiss/faiss/IndexPQFastScan.cpp
                    thirdparty/faiss/faiss/IndexIVFPQFastScan.cpp)
 

thirdparty/faiss/faiss/impl/simd_result_handlers.h

@@ -427,15 +427,15 @@ struct ReservoirTopN {
 
     void shrink() {
         uint64_t t0 = get_cy();
-        threshold = partition<C>(vals, ids, i, n);
+        threshold = partition_avx2<C>(vals, ids, i, n);
         i = n;
         cycles += get_cy() - t0;
     }
 
     void shrink_fuzzy() {
         uint64_t t0 = get_cy();
         assert(i == capacity);
-        threshold = partition_fuzzy<C>(
+        threshold = partition_fuzzy_avx2<C>(
                 vals, ids, capacity, n, (capacity + n) / 2, &i);
         cycles += get_cy() - t0;
     }

thirdparty/faiss/faiss/utils/partitioning.h

@@ -38,6 +38,27 @@ inline typename C::T partition(
     return partition_fuzzy<C>(vals, ids, n, q, q, nullptr);
 }
 
+// avx2 version
+template <class C>
+typename C::T partition_fuzzy_avx2(
+        typename C::T* vals,
+        typename C::TI* ids,
+        size_t n,
+        size_t q_min,
+        size_t q_max,
+        size_t* q_out);
+
+// avx2 version
+/** simplified interface for when the parition is not fuzzy */
+template <class C>
+inline typename C::T partition_avx2(
+        typename C::T* vals,
+        typename C::TI* ids,
+        size_t n,
+        size_t q) {
+    return partition_fuzzy_avx2<C>(vals, ids, n, q, q, nullptr);
+}
+
 /** low level SIMD histogramming functions */
 
 /** 8-bin histogram of (x - min) >> shift