ord: default thread count to number of available CPUs (#10350)#10724
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saurav-fermions wants to merge 1 commit into
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ord: default thread count to number of available CPUs (#10350)#10724saurav-fermions wants to merge 1 commit into
saurav-fermions wants to merge 1 commit into
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…roject#10350) OpenROAD previously booted with thread_count=1, so users who did not pass "-threads N" ran single-threaded without knowing it. Resolve the default thread count in the OpenRoad constructor via std::thread::hardware_concurrency(), i.e. behave like "-threads max" by default. An explicit "-threads N" / "-threads max" CLI flag and the set_thread_count Tcl command still override the default. A fallback of 1 thread is kept for the case hardware_concurrency() returns 0 (unable to determine CPU count). Determinism: regression tests are unaffected. Flow tests already call set_thread_count [cpu_count] and pin sta::set_thread_count 1; tool unit tests that care set their own thread count; the regression harness does not pass -threads by default. Verified utl/dpl/grt/rsz/gpl subsets pass with the new default. Signed-off-by: Saurav Singh <saurav.singh@fermions.co>
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This pull request updates the OpenRoad constructor in src/OpenRoad.cc to default the thread count to the number of available hardware CPUs (falling back to 1 if hardware concurrency cannot be determined). This ensures that the application does not silently run single-threaded when no explicit thread count is provided. There are no review comments, so no feedback is provided.
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Summary
Defaults
thread_countto the number of available CPUs instead of 1, so users who do not pass-threads Nno longer run single-threaded unknowingly. Explicit-threads Noverrides still work and regression-test determinism is preserved.Type of Change
Impact
Faster default runs on multi-core machines; explicit overrides unchanged.
Verification
thread_count1 -> nCPU;-threads Noverride verified.Related Issues
Fixes #10350
Developed with SAIGE, Fermions' autonomous RTL/EDA debugging agent; root-caused, tested, and signed off by the submitter (@saurav-fermions).