Add perf tests

AGENTS.md

@@ -8,7 +8,7 @@
   to retrieve VMware disk contents.
 - Integration tests under `tests/integration/` are a good starting point for
   interacting with the VMware NBD / NFC APIs. They take a session-scoped
-  `lab` fixture from `tests/integration/conftest.py` (credentials and VM
+  `lab` fixture from `tests/conftest.py` (credentials and VM
   settings in `tests.integration.base.LabEnv`). The fixture creates a
   temporary empty VM for the pytest session. We can make use of
   them to reverse engineer the VMware protocol, for example making various
@@ -41,7 +41,8 @@
   fixture creates one temporary empty VM with a 10 GiB disk for the whole
   run and destroys it at session end. Run them with
   `tox -e integration` or
-  `.venv/bin/pytest tests/integration`.
+  `.venv/bin/pytest tests/integration`. Throughput comparison against
+  native VDDK lives under `tests/perf/` (`tox -e perf`).
 
 
 ## Other rules

README.md

@@ -64,6 +64,7 @@ VDDK-shaped handle.
 | `openvixdisklib/nfc_auth.py`       | VIM login, NFC ticket, authd on 902                    |
 | `openvixdisklib/nfc_open.py`       | Classic NFC handshake, AIO open, sector read/write     |
 | `tests/integration/`               | Live pytest suite against a lab vCenter                |
+| `tests/perf/`                      | Throughput comparison of openvixdisklib vs VDDK        |
 | `tests/integration/vixdisklib.py`  | Native VDDK wrapper used only to cross-check           |
 | `docs/`                            | Protocol notes and reverse-engineering steps           |
 
@@ -95,6 +96,13 @@ tox -e integration
 .venv/bin/pytest tests/integration
 ```
 
+Compare write/read throughput of openvixdisklib and native VDDK
+(`64KiB`, 129-sector, and `32MiB` transfers):
+
+```bash
+tox -e perf
+```
+
 VDDK cross-check tests skip when `libvixDiskLib` is not loadable from
 `.vddk`. `tox -e integration` sets `LD_LIBRARY_PATH` to that directory
 and clears `LD_PRELOAD`. For a direct pytest run, do the same.

tox.ini

@@ -51,6 +51,15 @@ commands =
     pycobertura show --format html --source openvixdisklib \
         coverage.xml -o coverage.html
 
+[testenv:perf]
+description = Compare openvixdisklib and VDDK I/O throughput against the lab.
+sitepackages = True
+usedevelop = True
+setenv =
+    {[testenv:integration]setenv}
+commands =
+    python -m pytest -v -s tests/perf/ {posargs}
+
 [testenv:fmt]
 description = Format the code based on the coding style standards.
 deps =