(Feature): Check if swap is active; Drop VM caches and sync disk (#1042)

* (Feature): Check if swap is active; Drop VM caches and sync disk

* (fix): sysctl must be with sudo

* (Tests): Swap off for tests

Author: ArneTR

.github/actions/gmt-pytest/action.yml

@@ -98,6 +98,11 @@ runs:
     # - name: Setup upterm session
     #   uses: lhotari/action-upterm@v1
 
+    - name: Disable swap
+      shell: bash
+      run: |
+        sudo swapoff -a
+
     - name: Run Tests
       shell: bash
       working-directory: ${{ inputs.gmt-directory }}/tests

install_linux.sh

@@ -39,6 +39,10 @@ if [[ $build_sgx == true ]] ; then
     rm lib/sgx-software-enable/sgx_enable.o
 fi
 
+print_message "Enabling cache cleanup without sudo via sudoers entry"
+echo "ALL ALL=(ALL) NOPASSWD:/usr/sbin/sysctl -w vm.drop_caches=3" | sudo tee /etc/sudoers.d/green-coding-drop-caches
+sudo chmod 500 /etc/sudoers.d/green-coding-drop-caches
+
 print_message "Setting the cluster cleanup.sh file to be owned by root"
 sudo cp -f $PWD/tools/cluster/cleanup_original.sh $PWD/tools/cluster/cleanup.sh
 sudo chown root:root $PWD/tools/cluster/cleanup.sh

lib/system_checks.py

@@ -12,6 +12,7 @@
 import subprocess
 import psutil
 import locale
+import platform
 
 from psycopg import OperationalError as psycopg_OperationalError
 
@@ -73,6 +74,22 @@ def check_docker_daemon():
 def check_utf_encoding():
     return locale.getpreferredencoding().lower() == sys.getdefaultencoding().lower() == 'utf-8'
 
+# This text we compare with indicates that no swap is used
+#pylint: disable=no-else-return
+def check_swap_disabled():
+    if platform.system() == 'Darwin':
+        result = subprocess.check_output(['sysctl', 'vm.swapusage'], encoding='utf-8')
+        return result == 'vm.swapusage: total = 0.00M  used = 0.00M  free = 0.00M  (encrypted)'
+    else:
+        result = subprocess.check_output(['free'], encoding='utf-8')
+        for line in result.splitlines():
+            # we want this output: Swap:              0           0           0
+            # and condense it to Swap:000
+            if line.startswith('Swap') and line.replace(' ', '') != 'Swap:000':
+                return False
+        return True
+
+
 ######## END CHECK FUNCTIONS ########
 
 start_checks = [
@@ -85,6 +102,8 @@ def check_utf_encoding():
     (check_docker_daemon, Status.ERROR, 'docker daemon', 'The docker daemon could not be reached. Are you running in rootless mode or have added yourself to the docker group? See installation: [See https://docs.green-coding.io/docs/installation/]'),
     (check_containers_running, Status.WARN, 'running containers', 'You have other containers running on the system. This is usually what you want in local development, but for undisturbed measurements consider going for a measurement cluster [See https://docs.green-coding.io/docs/installation/installation-cluster/].'),
     (check_utf_encoding, Status.ERROR, 'utf file encoding', 'Your system encoding is not set to utf-8. This is needed as we need to parse console output.'),
+    (check_swap_disabled, Status.ERROR, 'swap disabled', 'Your system uses a swap filesystem. This can lead to very instable measurements. Please disable swap.'),
+
 ]
 
 def check_start():

runner.py

@@ -180,6 +180,14 @@ def save_notes_runner(self):
         print(TerminalColors.HEADER, '\nSaving notes: ', TerminalColors.ENDC, self.__notes_helper.get_notes())
         self.__notes_helper.save_to_db(self._run_id)
 
+    def clear_caches(self):
+        subprocess.check_output(['sync'])
+
+        if platform.system() == 'Darwin':
+            return
+        # 3 instructs kernel to drops page caches AND inode caches
+        subprocess.check_output(['sudo', '/usr/sbin/sysctl', '-w', 'vm.drop_caches=3'])
+
     def check_system(self, mode='start'):
         if self._skip_system_checks:
             print("System check skipped")
@@ -1579,6 +1587,7 @@ def run(self):
         try:
             config = GlobalConfig().config
             self.start_measurement() # we start as early as possible to include initialization overhead
+            self.clear_caches()
             self.check_system('start')
             self.initialize_folder(self._tmp_folder)
             self.checkout_repository()

tests/test_functions.py

@@ -161,6 +161,7 @@ def run_until(self, step):
         try:
             config = GlobalConfig().config
             self.__runner.start_measurement()
+            self.__runner.clear_caches()
             self.__runner.check_system('start')
             self.__runner.initialize_folder(self.__runner._tmp_folder)
             self.__runner.checkout_repository()