Stream: t-compiler

Topic: Can the rustc tests be more parallel?


Edd Barrett (Jun 03 2019 at 09:53, on Zulip):

Hi,

We just got a new machine for building/testing a fork of rust. The machine has loads of cores.

I was watching htop while x.py test was running and noticed that whilst some suites are highly parallel (e.g. rustdoc), others are not.

Is there any reason the tests cannot be more parallel?

Thanks!

pnkfelix (Jun 03 2019 at 10:12, on Zulip):

isn't there a flag you pass to increase the number of jobs used for tests?

pnkfelix (Jun 03 2019 at 10:13, on Zulip):

/me looks

pnkfelix (Jun 03 2019 at 10:16, on Zulip):

yeah, its in the x.py test --help output:

...
    -j, --jobs JOBS     number of jobs to run in parallel
...

would that resolve your issue?

pnkfelix (Jun 03 2019 at 10:18, on Zulip):

there is also a RUST_TEST_THREADS environment variable that I believe tells compiletest to run the tests on multiple threads ; you may need to use a combination of these two things to get the best utilization of a machine with many cores.

pnkfelix (Jun 03 2019 at 10:19, on Zulip):

(oh, but I think we already set that by default to the value sent in for --jobs, so the latter bit is probably unneccesary)

Last update: Nov 22 2019 at 04:40UTC