Re: [PATCH v2] perf tests: Improvements to build-test performance

[sashiko-bot@kernel.org]

> Replace hardcoded 'make' calls with '$(MAKE)' within tests/make to
> ensure GNU Make jobserver file descriptors are properly inherited by
> nested builds.
> 
> Additionally, remove the 'unexport MAKEFLAGS' from
> tools/perf/Makefile. This hack was originally added to prevent the
> wrapper's internal '-j$(JOBS)' override from crashing when parent
> jobserver tokens were present. Instead, use proper GNU Make
> conditionals to check for '-j' or 'jobserver' strings within
> MAKEFLAGS. If a jobserver is already orchestrating the build,
> gracefully back off and let GNU Make manage parallelism natively.
> 
> Finally, optimize the 'out' target (which processes 'run_O'
> out-of-tree builds) by stripping sequential bottlenecks like $(call
> clean) from isolated tmp directories, and wrapping the target list in
> a parallel sub-make call.
> 
> These combined changes enable 'build-test' out-of-tree targets to
> build completely concurrently without severing jobserver tokens.
> 
> Unscientifically measured the change lowered the build-test from
> around 15 minutes to 10 minutes on a 28 threaded Alderlake CPU. Fixing
> the jobserver issues meant the machine remained somewhat usable while
> running the test.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260903045603.3611902-1-irogers@google.com?part=1