Add cpu_weight config, relates to Systemd's CPUAccounting and CPUWeight

README.md

@@ -143,6 +143,7 @@ in your `jupyterhub_config.py` file:
 
 - **[`mem_limit`](#mem_limit)**
 - **[`cpu_limit`](#cpu_limit)**
+- **[`cpu_weight`](#cpu_weight)**
 - **[`user_workingdir`](#user_workingdir)**
 - **[`username_template`](#username_template)**
 - **[`default_shell`](#default_shell)**
@@ -214,6 +215,23 @@ This works out perfect for most cases, since this allows users to burst up and
 use all CPU when nobody else is using CPU & forces them to automatically yield
 when other users want to use the CPU.
 
+The share of access each user gets can be adjusted with the `cpu_weight` option.
+
+### `cpu_weight`
+
+An integer representing the share of CPU time each user can use. A user with
+a `cpu_weight` of 200 will get 2x access to the CPU than a user with a `cpu_weight`
+of 100, which is the system default.
+
+```python
+c.SystemdSpawner.cpu_weight = 100
+```
+
+Defaults to `None`, which implicitly means 100.
+
+This info is exposed to the single-user server as the environment variable
+`CPU_WEIGHT` as an integer.
+
 ### `user_workingdir`
 
 The directory to spawn each user's notebook server in. This directory is what users

systemdspawner/systemdspawner.py

@@ -5,7 +5,7 @@
 
 from jupyterhub.spawner import Spawner
 from jupyterhub.utils import random_port
-from traitlets import Bool, Dict, List, Unicode
+from traitlets import Bool, Dict, Integer, List, Unicode
 
 from systemdspawner import systemd
 
@@ -146,6 +146,18 @@ class SystemdSpawner(Spawner):
         """,
     ).tag(config=True)
 
+    cpu_weight = Integer(
+        None,
+        allow_none=True,
+        help="""
+        Assign a CPU weight to the single-user notebook server.
+        Available CPU time is allocated in proportion to each user's weight.
+
+        Acceptable value: an integer between 1 to 10000. 
+        System default is 100.
+        """,
+    ).tag(config=True)
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         # All traitlets configurables are configured by now
@@ -276,6 +288,9 @@ async def start(self):
             else:
                 working_dir = self._expand_user_vars(self.user_workingdir)
 
+        if self.cpu_weight:
+            env["CPU_WEIGHT"] = str(self.cpu_weight)
+
         if self.isolate_tmp:
             properties["PrivateTmp"] = "yes"
 
@@ -304,6 +319,11 @@ async def start(self):
             properties["CPUAccounting"] = "yes"
             properties["CPUQuota"] = f"{int(self.cpu_limit * 100)}%"
 
+        if self.cpu_weight is not None:
+            # FIXME: Detect & use proper properties for v1 vs v2 cgroups
+            properties["CPUAccounting"] = "yes"
+            properties["CPUWeight"] = str(self.cpu_weight)
+
         if self.disable_user_sudo:
             properties["NoNewPrivileges"] = "yes"