lttng: Tests: Add test for shm size warning

Change-Id: I20c5bc97f47288f308028d4c3c067a19e913a878
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/tests/regression/Makefile.am b/tests/regression/Makefile.am
index 90f5c512fef89abb7b74cf5eb2b89c8c67389127..9f4ec7ab86c3ffec7afcd299a6f5cb92027346a1 100644 (file)
--- a/tests/regression/Makefile.am
+++ b/tests/regression/Makefile.am
@@ -71,7 +71,8 @@ TESTS = tools/base-path/test_ust \
        tools/context/test_ust.py \
        tools/client/test_session_commands.py \
        tools/client/test_event_rule_listing.py \
-       tools/client/test_bug1373_events_differ_only_by_loglevel
+       tools/client/test_bug1373_events_differ_only_by_loglevel \
+       tools/client/test_warn_on_shm_too_small.py
 
 # Only build kernel tests on Linux.
 if IS_LINUX

diff --git a/tests/regression/tools/client/Makefile.am b/tests/regression/tools/client/Makefile.am
index 5a85480fd9cabb5fedb9deaa532645a88dfc313e..55f10e681db49f712d07cb6f104a91c389855d08 100644 (file)
--- a/tests/regression/tools/client/Makefile.am
+++ b/tests/regression/tools/client/Makefile.am
@@ -1,9 +1,11 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 noinst_SCRIPTS = test_session_commands.py test_event_rule_listing.py \
-       test_bug1373_events_differ_only_by_loglevel
+       test_bug1373_events_differ_only_by_loglevel \
+       test_warn_on_shm_too_small.py
 EXTRA_DIST = test_session_commands.py test_event_rule_listing.py \
-       test_bug1373_events_differ_only_by_loglevel
+       test_bug1373_events_differ_only_by_loglevel \
+       test_warn_on_shm_too_small.py
 
 all-local:
        @if [ x"$(srcdir)" != x"$(builddir)" ]; then \

diff --git a/tests/regression/tools/client/test_warn_on_shm_too_small.py b/tests/regression/tools/client/test_warn_on_shm_too_small.py
new file mode 100755 (executable)
index 0000000..ac9ff92
--- /dev/null
+++ b/tests/regression/tools/client/test_warn_on_shm_too_small.py
@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+#
+# SPDX-FileCopyrightText: 2024 Kienan Stewart <kstewart@efficios.com>
+# SPDX-LicenseIdentifier: GPL-2.0-only
+#
+
+"""
+Tests that the lttng command-line client emits a warning when the
+the a shared memory path for a session is smaller than an estimate
+of the minimum memory allocation required based on the number of
+sub-buffers, the sub-buffer size, the number of CPUs, and if the
+session is in snapshot mode or not.
+"""
+
+import math
+import os
+import pathlib
+import subprocess
+import sys
+import time
+
+test_utils_import_path = pathlib.Path(__file__).absolute().parents[3] / "utils"
+sys.path.append(str(test_utils_import_path))
+
+import lttngtest
+
+
+def test_shm_warning(tap, test_env, tests):
+    if os.getuid() != 0:
+        tap.skip_all_remaining("This test requires root to make a temporary shm mount")
+        return
+
+    # Create a 64M shm mount. Many containers default to a shm of this size.
+    # @see https://github.com/moby/moby/blob/a95a6788b59885056512c837897db20684433780/daemon/config/config.go#L39
+    # @see https://docs.podman.io/en/v5.3.0/markdown/podman-run.1.html#shm-size-number-unit
+    shm_path = lttngtest.TemporaryDirectory("tmp")
+    p = subprocess.Popen(
+        ["mount", "-t", "tmpfs", "-o", "size=64M", "tmpfs", str(shm_path.path)]
+    )
+    p.wait()
+    if p.returncode != 0:
+        tap.skip_all_remaining("Couldn't create tmpfs for testing alternate shm path")
+        return
+
+    shm_path.add_cleanup_callback(
+        lambda path: subprocess.Popen(["umount", path]).wait(), str(shm_path.path)
+    )
+
+    # This may not be the CPUs available on the system, as it could be limited
+    # by `-X cpu-count` or `PYTHON_CPU_COUNT` as of Python 3.13
+    ncpus = os.cpu_count()
+    if ncpus is None:
+        tap.skip_all_remaining("Cannot determine CPU count")
+        return
+
+    client = lttngtest.LTTngClient(test_env, log=tap.diagnostic)
+    for test in tests:
+        subbuf_count = 2 if test["snapshot"] else 1
+        subbuf_size = (
+            test["target_usage_mib"] / ncpus / test["nchannels"] / subbuf_count
+        )
+        if not math.log(subbuf_size, 2).is_integer():
+            tag.diagnostic(subbuf_size)
+            tap.skip("Sub-buffer size {} is not a power of 2".format(subbuf_size))
+            continue
+        subbuf_size = int(subbuf_size)
+
+        tap.diagnostic(
+            "Case: nCPUs {} with {} channels of {} sub-buffer(s) of size {}M [{}] {} warn".format(
+                ncpus,
+                test["nchannels"],
+                subbuf_count,
+                subbuf_size,
+                "snapshot enabled" if test["snapshot"] else "snapshot disabled",
+                "should" if test["warning_expected"] else "should not",
+            )
+        )
+
+        session = client.create_session(
+            output=None, shm_path=shm_path.path, snapshot=test["snapshot"]
+        )
+        channels = []
+        for channel in range(test["nchannels"]):
+            channel = session.add_channel(
+                lttngtest.lttngctl.TracingDomain.User,
+                lttngtest.lttngctl.BufferSharingPolicy.PerUID,
+                subbuf_size="{}M".format(subbuf_size),
+                subbuf_count=subbuf_count,
+            )
+            channel.add_recording_rule(
+                lttngtest.lttngctl.UserTracepointEventRule("tp:tptest")
+            )
+
+        output = client._run_cmd("start '{}'".format(session.name))
+        tap.diagnostic("\n{}\n".format(output))
+        session.destroy()
+        tap.test(
+            ("Warning" in output and test["warning_expected"])
+            or ("Warning" not in output and not test["warning_expected"]),
+            "Warning {} in lttng client output when starting session".format(
+                "present" if test["warning_expected"] else "not present"
+            ),
+        )
+
+
+if __name__ == "__main__":
+    tests = [
+        {
+            "warning_expected": False,
+            "target_usage_mib": 32,
+            "snapshot": False,
+            "nchannels": 1,
+        },
+        {
+            "warning_expected": True,
+            "target_usage_mib": 64,
+            "snapshot": False,
+            "nchannels": 1,
+        },
+        {
+            "warning_expected": True,
+            "target_usage_mib": 128,
+            "snapshot": False,
+            "nchannels": 1,
+        },
+        {
+            "warning_expected": False,
+            "target_usage_mib": 32,
+            "snapshot": True,
+            "nchannels": 1,
+        },
+        {
+            "warning_expected": True,
+            "target_usage_mib": 64,
+            "snapshot": True,
+            "nchannels": 1,
+        },
+        {
+            "warning_expected": False,
+            "target_usage_mib": 32,
+            "snapshot": False,
+            "nchannels": 2,
+        },
+        {
+            "warning_expected": True,
+            "target_usage_mib": 64,
+            "snapshot": False,
+            "nchannels": 2,
+        },
+    ]
+
+    tap = lttngtest.TapGenerator(len(tests))
+    with lttngtest.test_environment(log=tap.diagnostic, with_sessiond=True) as test_env:
+        test_shm_warning(tap, test_env, tests)