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| os | None |
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| git_commit |
commit 73a13839d3ec4dab9330b3909890105efad9b3bd Author: Hui <hui.xie1990@gmail.com> Date: Sun Dec 7 12:04:11 2025 +0000 [libc++] Allows any types of size 4 and 8 to use native platform ulock_wait (#161086) This is to address #146145 The issue before was that, for `std::atomic::wait/notify`, we only support `uint64_t` to go through the native `ulock_wait` directly. Any other types will go through the global contention table's `atomic`, increasing the chances of spurious wakeup. This PR tries to allow any types that are of size 4 or 8 to directly go to the `ulock_wait`. This PR is just proof of concept. If we like this idea, I can go further to update the Linux/FreeBSD branch and add ABI macros so the existing behaviours are reserved under the stable ABI Here are some benchmark results ``` Benchmark Time CPU Time Old Time New CPU Old CPU New ---------------------------------------------------------------------------------------------------------------------------------------------------- BM_stop_token_single_thread_reg_unreg_callback/1024 -0.1113 -0.1165 51519 45785 51397 45408 BM_stop_token_single_thread_reg_unreg_callback/4096 -0.2727 -0.1447 249685 181608 211865 181203 BM_stop_token_single_thread_reg_unreg_callback/65536 -0.1241 -0.1237 3308930 2898396 3300986 2892608 BM_stop_token_single_thread_reg_unreg_callback/262144 +0.0335 -0.1920 13237682 13681632 13208849 10673254 OVERALL_GEOMEAN -0.1254 -0.1447 0 0 0 0 ``` ``` Benchmark Time CPU Time Old Time New CPU Old CPU New ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- BM_1_atomic_1_waiter_1_notifier<KeepNotifying, NumHighPrioTasks<0>>/65536 -0.3344 -0.2424 5960741 3967212 5232250 3964085 BM_1_atomic_1_waiter_1_notifier<KeepNotifying, NumHighPrioTasks<0>>/131072 -0.1474 -0.1475 9144356 7796745 9137547 7790193 BM_1_atomic_1_waiter_1_notifier<KeepNotifying, NumHighPrioTasks<0>>/262144 -0.1336 -0.1340 18333441 15883805 18323711 15868500 OVERALL_GEOMEAN -0.2107 -0.1761 0 0 0 0 ``` ``` Benchmark Time CPU Time Old Time New CPU Old CPU New -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<2>, NumHighPrioTasks<0>>/16384 +0.2321 -0.0081 836618 1030772 833197 826476 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<2>, NumHighPrioTasks<0>>/32768 -0.3034 -0.1329 2182721 1520569 1747211 1515028 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<2>, NumHighPrioTasks<0>>/65536 -0.0924 -0.0924 3389098 3075897 3378486 3066448 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<8>, NumHighPrioTasks<0>>/4096 +0.0464 +0.0474 664233 695080 657736 688892 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<8>, NumHighPrioTasks<0>>/8192 -0.0279 -0.0267 1336041 1298794 1324270 1288953 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<8>, NumHighPrioTasks<0>>/16384 +0.0270 +0.0304 2543004 2611786 2517471 2593975 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<32>, NumHighPrioTasks<0>>/1024 +0.0423 +0.0941 473621 493657 325604 356245 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<32>, NumHighPrioTasks<0>>/2048 +0.0420 +0.0675 906266 944349 636253 679169 BM_1_atomic_multi_waiter_1_notifier<KeepNotifying, NumWaitingThreads<32>, NumHighPrioTasks<0>>/4096 +0.0359 +0.0378 1761584 1824783 1015092 1053439 OVERALL_GEOMEAN -0.0097 -0.0007 0 0 0 0 ``` ``` Benchmark Time CPU Time Old Time New CPU Old CPU New --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<2>, NumHighPrioTasks<0>>/4096 -0.0990 -0.1001 371100 334370 369984 332955 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<2>, NumHighPrioTasks<0>>/8192 -0.0305 -0.0314 698228 676908 696418 674585 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<2>, NumHighPrioTasks<0>>/16384 -0.0258 -0.0268 1383530 1347894 1380665 1343680 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<8>, NumHighPrioTasks<0>>/1024 +0.0465 +0.4702 937821 981388 472087 694082 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<8>, NumHighPrioTasks<0>>/2048 +0.1596 +0.9140 1704819 1976899 616419 1179852 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<8>, NumHighPrioTasks<0>>/4096 -0.1018 -0.2316 3793976 3407609 1912209 1469331 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<32>, NumHighPrioTasks<0>>/256 +0.0395 +0.5818 30102662 31292982 174650 276270 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<32>, NumHighPrioTasks<0>>/512 -0.0065 +1.2860 33079634 32863968 162150 370680 BM_N_atomics_N_waiter_N_notifier<KeepNotifying, NumberOfAtomics<32>, NumHighPrioTasks<0>>/1024 -0.0325 +0.4683 36581740 35392385 282320 414520 OVERALL_GEOMEAN -0.0084 +0.2878 0 0 0 0 ``` --------- Co-authored-by: Louis Dionne <ldionne.2@gmail.com> |
Filter
ldionne-old-macbook-results test results
| Run | Order | Start Time | Duration |
|---|---|---|---|
| Current | 561816 | 2025-12-16T16:40:01 | 0:00:00 |
| Previous | 561801 | 2025-12-16T16:40:01 | 0:00:00 |
| Baseline | 485288 | 2025-12-16T16:40:01 | 0:00:00 |
Tests Summary
| Status Group | # | # (B) |
|---|---|---|
| Performance Regressions | 2 | 0 |
| Performance Improvements | 7 | 0 |
| Added Tests | 0 | 16 |
| Unchanged Tests | 71 | 64 |
| Total Tests | 80 |
| Performance Regressions - execution_time | Δ | Previous | Current | σ | Δ (B) | σ (B) |
|---|---|---|---|---|---|---|
| 727_cppcheck_r | 1.91% | 24.584 | 25.054 | - | 0.00% | - |
| 748_flightdm_r | 1.09% | 8.948 | 9.045 | - | 0.00% | - |
| Performance Improvements - execution_time | Δ | Previous | Current | σ | Δ (B) | σ (B) |
|---|---|---|---|---|---|---|
| 735_gem5_r | -4.42% | 13.977 | 13.360 | - | 0.00% | - |
| 709_cactus_r | -1.70% | 20.032 | 19.691 | - | 0.00% | - |
| 737_gmsh_r | -1.62% | 12.941 | 12.732 | - | 0.00% | - |
| 766_femflow_r | -1.39% | 12.951 | 12.771 | - | 0.00% | - |
| 729_abc_r | -1.25% | 18.631 | 18.398 | - | 0.00% | - |
| 723_llvm_r | -1.15% | 11.522 | 11.390 | - | 0.00% | - |
| 707_ntest_r | -1.08% | 16.660 | 16.480 | - | 0.00% | - |
| Added Tests - execution_time |
|---|
| 706_stockfish_r |
| 707_ntest_r |
| 709_cactus_r |
| 710_omnetpp_r |
| 721_gcc_r |
| 723_llvm_r |
| 727_cppcheck_r |
| 729_abc_r |
| 731_astcenc_r |
| 735_gem5_r |
| 736_ocio_r |
| 737_gmsh_r |
| 748_flightdm_r |
| 750_sealcrypto_r |
| 753_ns3_r |
| 766_femflow_r |
Report Time: 0.14s