feature(test_runner): support choosing Pageserver VirtualFile IO engine

test_runner/fixtures/neon_fixtures.py

@@ -440,6 +440,7 @@ class NeonEnvBuilder:
         preserve_database_files: bool = False,
         initial_tenant: Optional[TenantId] = None,
         initial_timeline: Optional[TimelineId] = None,
+        pageserver_virtual_file_io_engine: Optional[str] = None,
     ):
         self.repo_dir = repo_dir
         self.rust_log_override = rust_log_override
@@ -473,6 +474,8 @@ class NeonEnvBuilder:
         self.test_overlay_dir = test_overlay_dir
         self.overlay_mounts_created_by_us: List[Tuple[str, Path]] = []
 
+        self.pageserver_virtual_file_io_engine: Optional[str] = pageserver_virtual_file_io_engine
+
         assert test_name.startswith(
             "test_"
         ), "Unexpectedly instantiated from outside a test function"
@@ -870,6 +873,8 @@ class NeonEnv:
         self.control_plane_api: str = f"http://127.0.0.1:{attachment_service_port}"
         self.attachment_service: NeonAttachmentService = NeonAttachmentService(self)
 
+        self.pageserver_virtual_file_io_engine = config.pageserver_virtual_file_io_engine
+
         # Create a config file corresponding to the options
         cfg: Dict[str, Any] = {
             "default_tenant_id": str(self.initial_tenant),
@@ -901,6 +906,9 @@ class NeonEnv:
                 "pg_auth_type": pg_auth_type,
                 "http_auth_type": http_auth_type,
             }
+            if self.pageserver_virtual_file_io_engine is not None:
+                ps_cfg["virtual_file_io_engine"] = self.pageserver_virtual_file_io_engine
+
             # Create a corresponding NeonPageserver object
             self.pageservers.append(
                 NeonPageserver(
@@ -1040,6 +1048,7 @@ def _shared_simple_env(
     neon_binpath: Path,
     pg_distrib_dir: Path,
     pg_version: PgVersion,
+    pageserver_virtual_file_io_engine: str,
 ) -> Iterator[NeonEnv]:
     """
     # Internal fixture backing the `neon_simple_env` fixture. If TEST_SHARED_FIXTURES
@@ -1068,6 +1077,7 @@ def _shared_simple_env(
         preserve_database_files=pytestconfig.getoption("--preserve-database-files"),
         test_name=request.node.name,
         test_output_dir=test_output_dir,
+        pageserver_virtual_file_io_engine=pageserver_virtual_file_io_engine,
     ) as builder:
         env = builder.init_start()
 
@@ -1105,6 +1115,7 @@ def neon_env_builder(
     run_id: uuid.UUID,
     request: FixtureRequest,
     test_overlay_dir: Path,
+    pageserver_virtual_file_io_engine: str,
 ) -> Iterator[NeonEnvBuilder]:
     """
     Fixture to create a Neon environment for test.
@@ -1133,6 +1144,7 @@ def neon_env_builder(
         broker=default_broker,
         run_id=run_id,
         preserve_database_files=pytestconfig.getoption("--preserve-database-files"),
+        pageserver_virtual_file_io_engine=pageserver_virtual_file_io_engine,
         test_name=request.node.name,
         test_output_dir=test_output_dir,
         test_overlay_dir=test_overlay_dir,

test_runner/fixtures/parametrize.py

@@ -8,7 +8,7 @@ from _pytest.python import Metafunc
 from fixtures.pg_version import PgVersion
 
 """
-Dynamically parametrize tests by Postgres version and build type (debug/release/remote)
+Dynamically parametrize tests by Postgres version, build type (debug/release/remote), and possibly by other parameters
 """
 
 
@@ -31,11 +31,12 @@ def build_type(request: FixtureRequest) -> Optional[str]:
     return None
 
 
-def pytest_generate_tests(metafunc: Metafunc):
-    # Do not parametrize performance tests yet, we need to prepare grafana charts first
-    if "test_runner/performance" in metafunc.definition._nodeid:
-        return
+@pytest.fixture(scope="function", autouse=True)
+def pageserver_virtual_file_io_engine(request: FixtureRequest) -> Optional[str]:
+    return None
 
+
+def pytest_generate_tests(metafunc: Metafunc):
     if (v := os.environ.get("DEFAULT_PG_VERSION")) is None:
         pg_versions = [version for version in PgVersion if version != PgVersion.NOT_SET]
     else:
@@ -46,5 +47,14 @@ def pytest_generate_tests(metafunc: Metafunc):
     else:
         build_types = [bt.lower()]
 
+    # A hacky way to parametrize performance tests only for `pageserver_virtual_file_io_engine=tokio-epoll-uring`
+    # And do not change test name for default `pageserver_virtual_file_io_engine=std-fs` to keep perf tests statistics
+    if (io_engine := os.environ.get("PAGESERVER_VIRTUAL_FILE_IO_ENGINE", "")) not in ("", "std-fs"):
+        metafunc.parametrize("pageserver_virtual_file_io_engine", [io_engine])
+
+    # Do not parametrize performance tests yet by Postgres version or build type, we need to prepare grafana charts first
+    if "test_runner/performance" in metafunc.definition._nodeid:
+        return
+
     metafunc.parametrize("build_type", build_types)
     metafunc.parametrize("pg_version", pg_versions, ids=map(lambda v: f"pg{v}", pg_versions))