diff --git a/cute_shm/core.py b/cute_shm/core.py
index 5dd57d9..44d9d5e 100644
--- a/cute_shm/core.py
+++ b/cute_shm/core.py
@@ -89,6 +89,8 @@ def bytes_to_human(size_bytes: int) -> str:
     if size_bytes == 0:
         return "0 bytes"
     size_name = ("bytes", "KB", "MB", "GB", "TB", "PB")
+    if size_bytes <= 0:
+        return "<unknown>"
     i = int(math.floor(math.log(size_bytes, 1024)))
     p = math.pow(1024, i)
     s = round(size_bytes / p, 2)
diff --git a/cute_shm/evaluation.py b/cute_shm/evaluation.py
index ad95ce0..64396b6 100644
--- a/cute_shm/evaluation.py
+++ b/cute_shm/evaluation.py
@@ -11,7 +11,7 @@
 from rich.console import Console
 from rich.table import Table
 
-from .core import ArrayDict
+from .core import ArrayDict, bytes_to_human
 from .hdf5_shm import unlinked_hdf5_to_shm
 from .numpy_shm import shm_to_arrays
 
@@ -51,7 +51,10 @@ def access_data(key, array):
         for key, array in shm_arrays.items():
             access_data(key, array)
     end_time = time.time()
-    result["frequency"] = iterations / (end_time - start_time)
+    try:
+        result["frequency"] += iterations / (end_time - start_time)
+    except KeyError:
+        result["frequency"] = iterations / (end_time - start_time)
 
 
 def access_directly(
@@ -72,22 +75,45 @@ def access_data(key, dataset):
         for key, dataset in data_dict.items():
             access_data(key, dataset)
     end_time = time.time()
-    result["frequency"] = iterations / (end_time - start_time)
+    try:
+        result["frequency"] += iterations / (end_time - start_time)
+    except KeyError:
+        result["frequency"] = iterations / (end_time - start_time)
 
 
-from .core import bytes_to_human
-
-
-def monitor_ram_usage(
-    stop_event: multiprocessing.Event, result: multiprocessing.Manager().dict
+def _monitor_ram_usage(
+    stop_event: multiprocessing.Event, max_value: multiprocessing.Value
 ) -> None:
     max_ram_usage = 0
     while not stop_event.is_set():
-        ram_usage = psutil.virtual_memory().used
+        memory = psutil.virtual_memory()
+        ram_usage = memory.total - memory.available
         if ram_usage > max_ram_usage:
             max_ram_usage = ram_usage
-        time.sleep(0.1)
-    result["max_ram_usage"] = max_ram_usage
+        time.sleep(0.01)
+    max_value.value = max_ram_usage
+
+
+from contextlib import contextmanager
+
+
+class RAM_Monitor:
+
+    @classmethod
+    def start(cls):
+        cls._manager = multiprocessing.Manager()
+        cls._max_usage = multiprocessing.Value("Q", 0)
+        cls._stop_event = multiprocessing.Event()
+        cls._ram_monitor = multiprocessing.Process(
+            target=_monitor_ram_usage, args=(cls._stop_event, cls._max_usage)
+        )
+        cls._ram_monitor.start()
+
+    @classmethod
+    def stop(cls) -> int:
+        cls._stop_event.set()
+        cls._ram_monitor.join()
+        return cls._max_usage.value
 
 
 def run_experiment(
@@ -101,13 +127,10 @@ def run_experiment(
 
     manager = multiprocessing.Manager()
     results = manager.dict()
-    stop_event = multiprocessing.Event()
 
-    ram_monitor = multiprocessing.Process(
-        target=monitor_ram_usage, args=(stop_event, results)
-    )
-    ram_monitor.start()
+    RAM_Monitor.start()
 
+    ts1 = time.time()
     processes = []
     for _ in range(num_processes):
         if use_shm:
@@ -120,16 +143,16 @@ def run_experiment(
                 target=access_directly, args=(data_dict, iterations, results)
             )
         processes.append(p)
+
+    for p in processes:
         p.start()
 
     for p in processes:
         p.join()
 
-    stop_event.set()
-    ram_monitor.join()
+    max_ram_usage = RAM_Monitor.stop()
 
     avg_frequency = results["frequency"] / num_processes
-    max_ram_usage = results["max_ram_usage"]
 
     return {
         "num_processes": num_processes,
@@ -147,7 +170,7 @@ def evaluation():
     parser.add_argument(
         "--iterations",
         type=int,
-        default=1000,
+        default=5000,
         help="Number of iterations for each process",
     )
     args = parser.parse_args()
@@ -167,7 +190,11 @@ def evaluation():
     table.add_column("Max RAM Usage (Direct Access)", justify="center")
 
     logging.info("Loading data from HDF5 file to the RAM (direct, no shared memory)")
+    RAM_Monitor.start()
     data_dict = hdf5_to_dict(hdf5_path)
+    logging.info(
+        f"Max observed RAM usage during load: {bytes_to_human(RAM_Monitor.stop())}"
+    )
 
     logging.info("Running experiments with direct access to the RAM")
     direct_results = []
@@ -187,7 +214,11 @@ def evaluation():
     data_dict = None
 
     logging.info("Loading data from HDF5 file to the shared memory")
+    RAM_Monitor.start()
     with unlinked_hdf5_to_shm(hdf5_path, project_name, overwrite=True, progress=True):
+        logging.info(
+            f"Max observed RAM usage during load: {bytes_to_human(RAM_Monitor.stop())}"
+        )
         logging.info("Running experiments with shared memory")
         shm_results = []
         for num_processes in [1, 5, 10, 15]:
@@ -207,8 +238,8 @@ def evaluation():
             str(direct_result["num_processes"]),
             f"{shm_result['avg_frequency']:.2f}",
             f"{direct_result['avg_frequency']:.2f}",
-            psutil._common.bytes2human(shm_result["max_ram_usage"]),
-            psutil._common.bytes2human(direct_result["max_ram_usage"]),
+            bytes_to_human(shm_result["max_ram_usage"]),
+            bytes_to_human(direct_result["max_ram_usage"]),
         )
 
     console.print(table)
diff --git a/pyproject.toml b/pyproject.toml
index 714bbbf..8955930 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "cute-shm"
-version = "1.01"
+version = "1.02"
 description = "managing np arrays stored in the shared memory"
 authors = [
 	"Vincent Berenz <vberenz@tuebingen.mpg.de>",