tuner: update binary search in tuner decision script.

Today, this implementation assumes that there are no repeated regions,
as every algo-proto choice has a single region.
E.g. tree-ll, tree-ll128, tree-ll, tree-ll128 won't work if the binary
search happens to have min and max sizes in two distinct
regions of same algo-proto choice.
This change makes it continue unless the max and min sizes diff by
2x, which we assume is too granular to define two regions.

Signed-off-by: Feng Ji <fengnji@amazon.com>

Author: fengjica

contrib/python/ofi_nccl/tuner/cli/wrapper.py

@@ -2,6 +2,7 @@
 
 import ctypes
 import logging
+import math
 import pandas as pd
 import numpy as np
 import os
@@ -185,7 +186,7 @@ def analyze_message_range(self, coll_type: NCCLFunc, min_size: int, max_size: in
         def bisect(min_size, max_size):
             min_decision = self.get_coll_info(coll_type, min_size)
             max_decision = self.get_coll_info(coll_type, max_size)
-            if min_decision == max_decision or max_size - min_size <= 1:
+            if (min_decision == max_decision and math.log2(max_size) - math.log2(min_size) <= 1) or max_size - min_size <= 1:
                 return [(min_size, min_decision), (max_size, max_decision)]
 
             mid_size = (min_size + max_size) // 2