[llvm-dev] Running lit (googletest) tests remotely

[Pavel Labath via llvm-dev]

Thank you all for the pointers. I am going to look at these to see if
there is anything that we could reuse, and come back. In the mean
time, I'll reply to Mathiass's comments:

On 26 May 2017 at 19:11, Matthias Braun <mbraun at apple.com> wrote:
>> Based on a not-too-detailed examination of the lit codebase, it does
>> not seem that it would be too difficult to add this capability: During
>> test discovery phase, we could copy the required files to the remote
>> host. Then, when we run the test, we could just prefix the run command
>> similarly to how it is done for running the tests under valgrind. It
>> would be up to the user to provide a suitable command for copying and
>> running files on the remote host (using rsync, ssh, telnet or any
>> other transport he chooses).
>
> This seems to be the crux to me: What does "required files" mean?
> - All the executables mentioned in the RUN line? What llvm was compiled as a library, will we copy those too?
For executables, I was considering just listing them explicitly (in
lit.local.cfg, I guess), although parsing the RUN line should be
possible as well. Even with RUN parsing, I expect we would some way to
explicitly add files to the copy list (e.g. for lldb tests we also
need to copy the program we are going to debug).

As for libraries, I see a couple of solutions:
- declare these configurations unsupported for remote executions
- copy over ALL shared libraries
- have automatic tracking of runtime dependencies - all of this
information should pass through llvm_add_library macro, so it should
be mostly a matter of exporting this information out of cmake.
These can be combined in the sense that we can start in the
"unsupported" state, and then add some support for it once there is a
need for it (we don't need it right now).

> - Can tests include other files? Do they need special annotations for that?
My initial idea was to just copy over all files in the Inputs folder.
Do you know of any other dependencies that I should consider?

>
> As another example: The llvm-testsuite can perform remote runs (test-suite/litsupport/remote.py if you want to see the implementation) that code makes the assumption that the remote devices has an NFS mount so the relevant parts of the filesystem look alike on the host and remote device. I'm not sure that is the best solution as NFS introduces its own sort of flakiness and potential skew in I/O heavy benchmarks but it avoids the question of what to copy to the device.

Requiring an NFS mount is a non-starter for us (no way to get an
android device to create one), although if we would be able to hook in
a custom script which does a copy to simulate the "mount", we might be
able to work with it. Presently I am mostly thinking about correctness
tests, and I am not worried about benchmark skews

regards,
pl