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Jon Ross-Perkins
7181a37997
Trying to make it easier to see possible bottlenecks. Disabling hyperthreading seems like a significant reduction in contention (15% improvement for me). Going down by half again reduces a contention a little further, but not significantly from what I see. My thought is that just flipping the flag is going to work best for people cross-system versus a "divide by four", but welcome to other opinions there. Note, I'm not digging into the source of the contention here, just observing it. Current default on my system (equivalent to `--threads=128`): ``` Running tests with 128 thread(s) ... Ran 1272 tests in 3955 ms wall time, 397615 ms across threads ``` Disabling hyperthreads (equivalent to `--threads=64`): ``` Running tests with 64 thread(s) ... Ran 1272 tests in 3520 ms wall time, 161957 ms across threads ``` `--threads=32`: ``` Running tests with 32 thread(s) ... Ran 1272 tests in 3329 ms wall time, 69327 ms across threads ``` And for `./autoupdate_testdata.py --threads=64 --print_slowest_tests=5`: ``` Running tests with 64 thread(s) ... Ran 1272 tests in 3417 ms wall time, 157946 ms across threads Slowest tests: - toolchain/lower/testdata/function/generic/call_recursive_basic.carbon: 1508 ms, 1484 ms in Run - toolchain/lower/testdata/builtins/print_read.carbon: 1506 ms, 1506 ms in Run - toolchain/lower/testdata/array/field.carbon: 1488 ms, 1487 ms in Run - toolchain/lower/testdata/builtins/int.carbon: 1482 ms, 1475 ms in Run - toolchain/lower/testdata/function/definition/params_one.carbon: 1472 ms, 1471 ms in Run ``` In test: ``` ==================== Test output for //toolchain/testing:file_test: Running tests with 64 thread(s) ... Ran 1272 tests in 2968 ms wall time, 177732 ms across threads Slowest tests: - toolchain/lower/testdata/builtins/int.carbon: 1544 ms, 1533 ms in Run - toolchain/lower/testdata/array/function_param.carbon: 1539 ms, 1537 ms in Run - toolchain/lower/testdata/basics/zero.carbon: 1537 ms, 1536 ms in Run - toolchain/lower/testdata/function/call/params_one.carbon: 1535 ms, 1534 ms in Run - toolchain/lower/testdata/function/definition/params_zero.carbon: 1531 ms, 1531 ms in Run [==========] Running 1272 tests from 1 test suite. [----------] Global test environment set-up. ```