Use -j$(nproc) for builds - #11313
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The ubuntu-24.04 runner has 4 vCPUs. The three native builds and the bsim build run with -j2; the Zephyr build honours make's jobserver (BUILD_JOB_SERVER_AWARE), so half the cores sit idle for the 3.3 minutes each of them takes.
dhalbert
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Sep 4, 2026
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How about -j$(nproc) ?
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Absolutely, I'll push it in the next commit once the CI runs here and I check to see how it went. |
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I would say change all |
Take the job count from the runner, so a change in runner CPUs needs no edit here.
Same change for the unix tests, mpy-cross, docs, the custom board build and the broadcom toolchain. The macOS job uses sysctl, which is what that platform has.
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Sep 5, 2026
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Great, thanks for making this uniform for all -j invocations.
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The native_sim, bsim and the two bsim board builds in this job run with -j2 on a runner with 4 vCPUs, and ninja inherits the limit through the jobserver. Half the machine is idle for the build phase, about 11 of the job's 42 minutes (3.3 + 1.1 + 3.3 + 3.0). -j4 is what the other workflows use.