Bazel running times in CI for a no-op build

[oharboe]

This is a no-op build, I only fixed some bazel lints https://jenkins.openroad.tools/job/OpenROAD-Public/job/PR-8548-head/2/pipeline-overview/log?nodeId=62

8 minutes to warm up Bazel... Is there a way around this?

[2025-10-05T07:00:21.337Z] + bazelisk test --config=ci --show_timestamps --test_output=errors --curses=no --force_pic --remote_header=Authorization=Basic **** --profile=build.profile ...
[deleted]
[2025-10-05T07:07:56.660Z] (07:07:56) INFO: Analyzed 1112 targets (508 packages loaded, 49620 targets configured).

critical path is 65 seconds, unsure why this test re-ran(presumably runfiles are not set up for cached tests).

 === PHASE SUMMARY INFORMATION ===
 
 Total launch phase time                              0.000 s    0.00%
 Total init phase time                               13.285 s    2.51%
 Total target pattern evaluation phase time         146.410 s   27.64%
 Total interleaved loading, analysis and execution phase time  366.621 s   69.21%
 Total finish phase time                              0.021 s    0.00%
 Total unknown phase time                             3.366 s    0.64%
 ---------------------------------------------------------------------
 Total run time                                     529.705 s  100.00%
 
 Critical path (65.516 s):
        Time Percentage   Description
      183 ms    0.28%   action 'Creating source manifest for //test/orfs/mock-array MockArray_4x4_flat_test'
    65.094 s   99.36%   action 'Creating runfiles tree bazel-out/k8-fastbuild/bin/test/orfs/mock-array/make_MockArray_4x4_flat_test_4x4_flat_test.runfiles'
     14.3 ms    0.02%   runfiles for //test/orfs/mock-array MockArray_4x4_flat_test
      224 ms    0.34%   action 'Testing //test/orfs/mock-array MockArray_4x4_flat_test'

[maliberty]

I don't know a way as we use a fresh VM for each job and so there will be no bazel server running. @QuantamHD @hzeller ideas?

[hzeller]

Next to the usual suspects to check (is there anything that is downloaded from anywhere or does everything come from a local bazel cache etc.) It sounds like just the overhead of spinning up VM.

Do you catpure and restore the disk cache when you tear down/set up the VM ?

My first starting point would be to create a trace profile and see what is happening
https://bazel.build/advanced/performance/json-trace-profile
(Don't know how well it captures IO costs).

[maliberty]

We do not capture the cache. If the cost is analyzing then I'm not clear that would help.

[hzeller]

analyze will also mean downloading the dependencies I think. So if it has to download large things such as the llvm toolchain this might be a factor.

[maliberty]

@sombraSoft @vvbandeira do you have a good way to measure this? Since it is in the CI is is trickier to measure locally.