code: def _knn_function(self, xq, xb, k, metric, thread_id=None):
      try:
          return faiss.knn_gpu(
              self.all_gpu_resources[thread_id],
              xq,
              xb,
              k,
              metric=metric,
              device=thread_id,
              vectorsMemoryLimit=self.knn_vectors_memory_limit,
              queriesMemoryLimit=self.knn_queries_memory_limit,
          )
      except Exception:
          logging.info(f"knn_function failed: {xq.shape}, {xb.shape}")
          raise
  
imports: import faiss
  import numpy
  import os
  from tqdm import tqdm, trange
  import sys
  import logging
  from faiss.contrib.ondisk import merge_ondisk
  from faiss.contrib.big_batch_search import big_batch_search
  from faiss.contrib.exhaustive_search import knn_ground_truth
  from faiss.contrib.evaluation import knn_intersection_measure
  from utils import get_intersection_cardinality_frequencies, margin, is_pretransform_index
  from dataset import create_dataset_from_oivf_config
label_desc: Use image node_id 15 for calling the OfflineIVF obj's underlying member method code with example usage: obj._knn_function(xq, xb, k, metric, thread_id) and returns: faiss