Multi tool use

LLVM lit testing: is it possible to configure number of threads via `lit.cfg`?

I wonder if it's possible to configure the number of threads for testing in a lit.cfg file.

lit.cfg

lit offers a command-line flag for specifying the number of threads:

llvm/utils/lit/lit.py -j1 <test directory>


lit


llvm/utils/lit/lit.py -j1 <test directory>


However, I'm not sure how to do this in a lit.cfg file. I want to force all tests in a subdirectory to be run with -j1 - not sure if this is possible.

lit.cfg

-j1

Edit: for reference, I'm working on the Swift codebase which has a large test suite (4000+ tests) with multiple test subdirectories.
I want to run just one subdirectory with -j1 and the rest with the default number of threads (-j12 for my machine).

-j1

-j12

1 Answer
1

I was wondering about that too a while back, but I don't think there is one because of this line here. Usually, the main project compilation times dwarf the lit tests execution time.

lit

It is easy to change, but I'd suggest using your build configuration to this (e.g. make or cmake). So, make test could execute something like lit -j $(nproc) underneath.

make

cmake

make test

lit -j $(nproc)

Edit (after OP update):

I haven't worked with the swift repo, but maybe you could hack your way around. One thing I could see is that you could influence the LIT_ARGS cmake variable with the options you want by appending to it.

swift

LIT_ARGS

cmake

Now to force a single process execution for a specific directory, you may add a lit.local.cfg that sets the singleProcess flag. This seems to override multi-thread execution:

lit.local.cfg

config.singleProcess = True


nproc

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.