diff --git a/.gitignore b/.gitignore
index 5d381cc..cb3d3be 100644
--- a/.gitignore
+++ b/.gitignore
@@ -160,3 +160,5 @@ cython_debug/
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
 
+/mnt/
+/img
\ No newline at end of file
diff --git a/src/main.py b/src/main.py
index 3fd6bcc..3323f38 100644
--- a/src/main.py
+++ b/src/main.py
@@ -5,30 +5,38 @@ import time
 
 BS = 1024**2
 
-def set_utilization(du, utilization_percent=0.6, baloon_filename='baloon'):
-    fs = os.path.realpath(du)
+def set_utilization(fs, utilization_percent=0.6, baloon_filename='baloon', hysteresis_percent=0.01):
+    fs = os.path.realpath(fs)
     du = disk_usage(fs)
-    print(f'total: {int(du.total/ 2**30)}GB, used: {int(du.used/ 2**30)}GB, free: {int(du.free/ 2**30)}GB')
-    to_be_wasted = int((du.total * utilization_percent) - du.used)
-    print(f'to_be_wasted: {int(to_be_wasted/ 2**30)}GB')
-    if to_be_wasted < 0:
+    if utilization_percent < 0.1 or utilization_percent > 0.9:
+        raise ValueError('utilization_percent must be between 0.1 and 0.9')
+    if hysteresis_percent < 0.0001 or hysteresis_percent > 0.1:
+        raise ValueError('hysteresis_percent must be between 0.0001 and 0.1')
+    hysteresis = int(du.total * hysteresis_percent)
+    if hysteresis < BS: hysteresis = BS
+    print(f'hysteresis: {hysteresis}bytes')
+    print(f'total: {round(du.total/ 2**30, 3)}GB, used: {round(du.used/ 2**30, 3)}GB, free: {round(du.free/ 2**30, 3)}GB usage: {round(du.used * 100 / (du.used+du.free), 3)}%')
+    to_be_wasted = int(((du.used+du.free) * utilization_percent) - ((du.used+du.free) - du.free))
+    print(f'to_be_wasted: {round(to_be_wasted/ 2**30, 3)}GB ')
+    if to_be_wasted < -hysteresis:
         to_be_trimmed = abs(to_be_wasted)
         baloon_size = os.path.getsize(os.path.join(fs, baloon_filename))
         if  baloon_size> to_be_trimmed:
             os.truncate(os.path.join(fs, baloon_filename), baloon_size - to_be_trimmed)
-        else: print(f'can\'t trim {baloon_size} > {to_be_trimmed}')
-    elif to_be_wasted > 0:
+            print(f'trimmed {to_be_trimmed} Bytes')
+        else: print(f'can\'t trim {baloon_size} < {to_be_trimmed}Bytes')
+    elif to_be_wasted > hysteresis:
         with open(os.path.join(fs, baloon_filename) , 'ab') as f:
             last = 0
+            writed = to_be_wasted
             while to_be_wasted > 0:
                 if time.time() - last > 1:
-                    print('\r', end='')
-                    print(f'left {int(to_be_wasted/ 2**30)}GB                    ', end='')
+                    print(f'left {int(to_be_wasted/ 2**30)}GB                    \r', end='')
                     last = time.time()                          
                 write_size = min(to_be_wasted, BS)
                 f.write(b'x' * write_size)
                 to_be_wasted -= write_size
-            print('Done               ')
+            print(f'Done, added {writed} bytes')
                 
 
-set_utilization('.')
\ No newline at end of file
+