On Tue, 19 May 2020, Alexei Starovoitov wrote:
On Mon, May 18, 2020 at 12:23:10PM +0100, Alan Maguire wrote:
Getting a clean BPF selftests run involves ensuring latest trunk LLVM/clang are used, pahole is recent (>=1.16) and config matches the specified config file as closely as possible. Document all of this in the general README.rst file. Also note how to work around timeout failures.
Signed-off-by: Alan Maguire alan.maguire@oracle.com
tools/testing/selftests/bpf/README.rst | 46 ++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+)
diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst index 0f67f1b..b00eebb 100644 --- a/tools/testing/selftests/bpf/README.rst +++ b/tools/testing/selftests/bpf/README.rst @@ -1,6 +1,52 @@ ================== BPF Selftest Notes ================== +First verify the built kernel config options match the config options +specified in the config file in this directory. Test failures for +unknown helpers, inability to find BTF etc will be observed otherwise.
+To ensure the maximum number of tests pass, it is best to use the latest +trunk LLVM/clang, i.e.
+git clone https://github.com/llvm/llvm-project
+Build/install trunk LLVM:
+.. code-block:: bash
- git clone https://github.com/llvm/llvm-project
- cd llvm-project
- mkdir build/llvm
- cd build/llvm
- cmake ../../llvm/
- make
- sudo make install
- cd ../../
+Build/install trunk clang:
+.. code-block:: bash
- mkdir -p build/clang
- cd build/clang
- cmake ../../clang
- make
- sudo make install
these instructions are obsolete and partially incorrect. May be refer to Documentation/bpf/bpf_devel_QA.rst instead?
Sure; looks like there are up-to-date sections there on running BPF selftests and building LLVM manually. Perhaps I should add the notes about pahole etc there too? I should also have noted that without an up-to-date iproute2 failures will be observed also.
+When building the kernel with CONFIG_DEBUG_INFO_BTF, pahole +version 16 or later is also required for BTF function +support. pahole can be built from the source at
+https://github.com/acmel/dwarves
+It is often available in "dwarves/libdwarves" packages also, +but be aware that versions prior to 1.16 will fail with +errors that functions cannot be found in BTF.
+When running selftests, the default timeout of 45 seconds +can be exceeded by some tests. We can override the default +timeout via a "settings" file; for example:
+.. code-block:: bash
- echo "timeout=120" > tools/testing/selftests/bpf/settings
Is it really the case? I've never seen anything like this.
When running via "make run_tests" on baremetal systems I see test timeouts pretty consistently; e.g. from a bpf tree test run yesterday:
not ok 6 selftests: bpf: test_progs # TIMEOUT not ok 31 selftests: bpf: test_tunnel.sh # TIMEOUT not ok 38 selftests: bpf: test_lwt_ip_encap.sh # TIMEOUT not ok 40 selftests: bpf: test_tc_tunnel.sh # TIMEOUT not ok 42 selftests: bpf: test_xdping.sh # TIMEOUT not ok 43 selftests: bpf: test_bpftool_build.sh # TIMEOUT
These will only occur if running via "make run_tests", so running tests individually would not trigger these failures.
Alan