Use sio2jail on WSL (#265)

* Use sio2jail on WSL

WSL2 (released 2019) is based on a Linux VM. In general its behavior is
consistent with any other Linux system running in a VM, so there should
be no reason to discriminate WSL under `util.is_linux()`.

In the future, we might want to check for specific features such as
perf counters being supported, but that is an orthogonal concern.

I have tested with several people using WSL across relatively modern
laptops (Intel 8th gen and up) and in all cases the Intel PMU driver
passed through enough perf counters for sio2jail to work.

If we wanted to test support for sio2jail more thoroughly, I suspect the
best method might be to actually try running sio2jail or the perf tool.

* Improve diagnostic for sio2jail check failure

* Avoid nested quotes in f-string

src/sinol_make/__init__.py

@@ -38,7 +38,7 @@ def configure_parsers():
 
 
 def check_sio2jail():
-    if util.is_linux() and not sio2jail.check_sio2jail():
+    if sio2jail.sio2jail_supported() and not sio2jail.check_sio2jail():
         print(util.warning('Up to date `sio2jail` in `~/.local/bin/` not found, installing new version...'))
         try:
             if sio2jail.install_sio2jail():

src/sinol_make/commands/run/__init__.py

@@ -280,7 +280,7 @@ def configure_subparser(self, subparser):
                 After running the solutions, it compares the solutions\' scores with the ones saved in config.yml.'
         )
 
-        default_timetool = 'sio2jail' if util.is_linux() else 'time'
+        default_timetool = 'sio2jail' if sio2jail.sio2jail_supported() else 'time'
 
         parser.add_argument('-s', '--solutions', type=str, nargs='+',
                             help='solutions to be run, for example prog/abc{b,s}*.{cpp,py}')
@@ -764,7 +764,7 @@ def validate_arguments(self, args):
 
         def use_sio2jail():
             timetool_path = None
-            if not util.is_linux():
+            if not sio2jail.sio2jail_supported():
                 util.exit_with_error('As `sio2jail` works only on Linux-based operating systems,\n'
                                      'we do not recommend using operating systems such as macOS.\n'
                                      'Nevertheless, you can still run sinol-make by specifying\n'
@@ -789,12 +789,12 @@ def use_time():
 
         timetool_path, timetool_name = None, None
         preferred_timetool = self.contest.preferred_timetool()
-        if preferred_timetool == 'sio2jail' and util.is_linux():
+        if preferred_timetool == 'sio2jail' and sio2jail.sio2jail_supported():
             use_default_timetool = use_sio2jail
         elif preferred_timetool == 'time':
             use_default_timetool = use_time
         else:
-            use_default_timetool = use_sio2jail if util.is_linux() else use_time
+            use_default_timetool = use_sio2jail if sio2jail.sio2jail_supported() else use_time
 
         if args.time_tool is None and self.config.get('sinol_undocumented_time_tool', '') != '':
             if self.config.get('sinol_undocumented_time_tool', '') == 'sio2jail':

src/sinol_make/sio2jail/__init__.py

@@ -74,12 +74,14 @@ def install_sio2jail(directory=None):
 
 def check_perf_counters_enabled():
     """
-    Checks if `kernel.perf_event_paranoid` is set to -1.
-    :return:
+    Checks if sio2jail is able to use perf counters to count instructions.
     """
-    if not util.is_linux() or not check_sio2jail():
+    if not sio2jail_supported() or not check_sio2jail():
         return
 
+    with open('/proc/sys/kernel/perf_event_paranoid') as f:
+        perf_event_paranoid = int(f.read())
+
     sio2jail = get_default_sio2jail_path()
     test_file = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'perf_test.py')
     python_executable = sys.executable
@@ -94,9 +96,21 @@ def check_perf_counters_enabled():
         process.terminate()
 
     if output != "Test string\n":
-        util.exit_with_error("To use the recommended tool for measuring time called `sio2jail`, please:\n"
-                             "- execute `sudo sysctl kernel.perf_event_paranoid=-1` to make `sio2jail` work for\n"
-                             "  the current system session,\n"
-                             "- or add `kernel.perf_event_paranoid=-1` to `/etc/sysctl.conf`\n"
-                             "  and reboot to permanently make sio2jail work.\n"
-                             "For more details, see https://github.com/sio2project/sio2jail#running.\n")
+        max_perf_event_paranoid = 2
+        if perf_event_paranoid > max_perf_event_paranoid:
+            hint = (f"You have `kernel.perf_event_paranoid` set to `{perf_event_paranoid}`"
+                ", which might be preventing userspace perf counters from working.\n"
+                f"Try running: `sudo sysctl kernel.perf_event_paranoid={max_perf_event_paranoid}`\n"
+                "If that fixes the problem, you can set this permanently by adding "
+                f"`kernel.perf_event_paranoid={max_perf_event_paranoid}` to `/etc/sysctl.conf` and rebooting.\n")
+        else:
+            hint = ("Your kernel, drivers, or hardware might be too old.\n"
+                "Check if the Intel PMU driver is loaded: `dmesg | grep -i 'perf'`\n"
+                "You can also check if the perf tool works correctly: `perf stat -e instructions:u -- sleep 0`\n"
+                "(if perf can't be found, it might be located in: `/usr/lib/linux-tools/*/perf`).\n")
+        cmdline = " ".join(process.args)
+        util.exit_with_error(f"Failed performance counters test: `{cmdline}`\n"
+            + hint +
+            "Alternatively, you can run sinol-make without instruction counting"
+            ", by adding the `--time-tool time` flag.\n"
+            "For more details, see https://github.com/sio2project/sio2jail#running.\n")

src/sinol_make/util.py

@@ -321,9 +321,9 @@ def is_wsl():
 
 def is_linux():
     """
-    Function to check if the program is running on Linux and not WSL.
+    Function to check if the program is running on Linux (including WSL).
     """
-    return sys.platform == "linux" and not is_wsl()
+    return sys.platform == "linux"
 
 
 def is_macos():

tests/conftest.py

@@ -7,7 +7,7 @@
 import fnmatch
 import multiprocessing as mp
 
-from sinol_make import util
+from sinol_make import sio2jail, util
 from sinol_make.helpers import compile, paths, cache, oicompare
 from sinol_make.interfaces.Errors import CompilationError
 
@@ -99,7 +99,7 @@ def pytest_generate_tests(metafunc):
         time_tools = []
         if metafunc.config.getoption("time_tool") != []:
             time_tools = metafunc.config.getoption("time_tool")
-        elif util.is_linux():
+        elif sio2jail.sio2jail_supported():
             time_tools = ["sio2jail", "time"]
         else:
             time_tools = ["time"]
@@ -118,6 +118,6 @@ def pytest_collection_modifyitems(config, items: List[pytest.Item]):
 
     for item in items:
         if "sio2jail" in item.keywords:
-            if not util.is_linux() or config.getoption("--time-tool") == ["time"] or \
+            if not sio2jail.sio2jail_supported() or config.getoption("--time-tool") == ["time"] or \
                     config.getoption("--github-runner"):
                 item.add_marker(pytest.mark.skip(reason="sio2jail required"))

tests/test_sio2jail.py

@@ -9,7 +9,7 @@
 
 @pytest.mark.github_runner
 def test_install_sio2jail():
-    if sys.platform != 'linux':
+    if not sio2jail.sio2jail_supported():
         return
 
     try:
@@ -34,7 +34,7 @@ def test_install_sio2jail():
 
 @pytest.mark.github_runner
 def test_check_sio2jail():
-    if sys.platform != 'linux':
+    if not sio2jail.sio2jail_supported():
         return
 
     try:
@@ -59,7 +59,7 @@ def test_perf_counters_not_set():
     """
     Test `sio2jail.check_perf_counters_enabled` with perf counters disabled
     """
-    if sys.platform != 'linux':
+    if not sio2jail.sio2jail_supported():
         return
 
     sio2jail.install_sio2jail()
@@ -72,7 +72,7 @@ def test_perf_counters_set():
     """
     Test `sio2jail.check_perf_counters_enabled` with perf counters enabled
     """
-    if not util.is_linux():
+    if not sio2jail.sio2jail_supported():
         return
     sio2jail.check_perf_counters_enabled()
 
@@ -82,7 +82,7 @@ def test_updating():
     """
     Test updating sio2jail
     """
-    if sys.platform != 'linux':
+    if not sio2jail.sio2jail_supported():
         return
     try:
         os.remove(os.path.expanduser('~/.local/bin/oiejq'))