code: def _select_min_memory_chunk_region(
      self, possible_chunk_regions, chunk_infos
  ):
      # remove illegal regions
      illegal_regions = []
      for i in possible_chunk_regions:
          if not self._is_legal_region(i, chunk_infos):
              illegal_regions.append(i)
      for i in illegal_regions:
          if i in possible_chunk_regions:
              possible_chunk_regions.remove(i)
  
      if len(possible_chunk_regions) == 0:
          return None
  
      # get max possible chunk region
      max_possible_chunk_region = (
          min([i["region"][0] for i in possible_chunk_regions]),
          max([i["region"][1] for i in possible_chunk_regions]),
      )
  
      # get mem for chunk region
      regions_dict_list = []
      for region in possible_chunk_regions:
          cur_region = region.copy()
          cur_node_list, cur_region = self.reorder_graph.tmp_reorder(
              self.node_mgr.get_node_list(), cur_region
          )
          cur_chunk_infos = chunk_infos + [cur_region]
          cur_mem_peak = (
              self.estimate_memory.estimate_chunk_inference_mem(
                  cur_node_list, cur_chunk_infos
              )[0]
          )
          cur_chunk_region_peak = cur_mem_peak[
              max_possible_chunk_region[0] : max_possible_chunk_region[
                  1
              ]
              + 1
          ]
          cur_chunk_region_max_peak = max(cur_chunk_region_peak)
          regions_dict_list.append(
              {
                  "chunk_info": region,
                  "chunk_max_mem": cur_chunk_region_max_peak,
                  "chunk_len": self._get_compute_node_num(
                      region["region"][0], region["region"][1]
                  ),
                  "reorder_chunk_info": cur_region,
                  "reorder_node_list": cur_node_list,
              }
          )
  
      # select the min mem
      chunk_max_mem = [i["chunk_max_mem"] for i in regions_dict_list]
      best_region_idx = chunk_max_mem.index(min(chunk_max_mem))
      best_region = regions_dict_list[best_region_idx]["chunk_info"]
      if best_region is not None:
          best_region["chunk_size"] = 1
      return best_region
  
file_path: ColossalAI/colossalai/autochunk/select_chunk.py
imports: from .estimate_memory import EstimateMemory
  from .reorder_graph import ReorderGraph
  from .trace_indice import TraceIndice
  from .utils import NodeMgr, is_non_compute_node
label_desc: Use image node_id 7 for calling the SelectChunk obj's underlying member method code with example usage: obj._select_min_memory_chunk_region(possible_chunk_regions, chunk_infos) and returns: best_region, None