Mach trap#-60
svc · mach trap -60
swtch
Legacy cooperative yield that hints the scheduler to run another runnable thread.
Prototype
kern_return_t swtch(/* 0 args */);Returns: kern_return_t
Version history
| XNU tag | macOS | # |
|---|---|---|
| xnu-123.5 | macOS 10.0 Cheetah | -59 |
| xnu-201 | macOS 10.1 Puma | -59 |
| xnu-344 | macOS 10.2 Jaguar | -59 |
| xnu-517 | macOS 10.3 Panther | -59 |
| xnu-792 | macOS 10.4 Tiger | -60 |
| xnu-1228 | macOS 10.5 Leopard | -60 |
| xnu-1456.1.26 | macOS 10.6 Snow Leopard | -60 |
| xnu-1699.24.8 | macOS 10.7 Lion | -60 |
| xnu-2050.18.24 | macOS 10.8 Mountain Lion | -60 |
| xnu-2422.115.4 | macOS 10.9 Mavericks | -60 |
| xnu-2782.40.9 | macOS 10.10 Yosemite | -60 |
| xnu-3247.1.106 | macOS 10.11 El Capitan | -60 |
| xnu-3789.1.32 | macOS 10.12 Sierra | -60 |
| xnu-4570.1.46 | macOS 10.13 High Sierra | -60 |
| xnu-4903.221.2 | macOS 10.14 Mojave | -60 |
| xnu-6153.11.26 | macOS 10.15 Catalina | -60 |
| xnu-7195.50.7.100.1 | macOS 11.0 Big Sur | -60 |
| xnu-8019.41.5 | macOS 12.0 Monterey | -60 |
| xnu-8792.41.9 | macOS 13.0 Ventura | -60 |
| xnu-10002.1.13 | macOS 14.0 Sonoma | -60 |
| xnu-11215.1.10 | macOS 15.0 Sequoia | -60 |
| xnu-11417.101.15 | macOS 15.4 Sequoia | -60 |
| xnu-12377.1.9 | macOS 26.0 Tahoe | -60 |
| xnu-10002.41.9 | — | -60 |
| xnu-10002.61.3 | — | -60 |
| xnu-10002.81.5 | — | -60 |
| xnu-10063.101.15 | — | -60 |
| xnu-10063.121.3 | — | -60 |
| xnu-10063.141.1 | — | -60 |
| xnu-11215.41.3 | — | -60 |
| xnu-11215.61.5 | — | -60 |
| xnu-11215.81.4 | — | -60 |
| xnu-11417.121.6 | — | -60 |
| xnu-11417.140.69 | — | -60 |
| xnu-1228.0.2 | — | -60 |
| xnu-1228.12.14 | — | -60 |
| xnu-1228.15.4 | — | -60 |
| xnu-1228.3.13 | — | -60 |
| xnu-1228.5.18 | — | -60 |
| xnu-1228.5.20 | — | -60 |
| xnu-1228.7.58 | — | -60 |
| xnu-1228.9.59 | — | -60 |
| xnu-12377.101.15 | — | -60 |
| xnu-12377.41.6 | — | -60 |
| xnu-12377.61.12 | — | -60 |
| xnu-12377.81.4 | — | -60 |
| xnu-124.1 | — | -59 |
| xnu-124.13 | — | -59 |
| xnu-124.7 | — | -59 |
| xnu-1486.2.11 | — | -60 |
| xnu-1504.15.3 | — | -60 |
| xnu-1504.3.12 | — | -60 |
| xnu-1504.7.4 | — | -60 |
| xnu-1504.9.17 | — | -60 |
| xnu-1504.9.26 | — | -60 |
| xnu-1504.9.37 | — | -60 |
| xnu-1699.22.73 | — | -60 |
| xnu-1699.22.81 | — | -60 |
| xnu-1699.24.23 | — | -60 |
| xnu-1699.26.8 | — | -60 |
| xnu-1699.32.7 | — | -60 |
| xnu-201.14 | — | -59 |
| xnu-201.19 | — | -59 |
| xnu-201.19.3 | — | -59 |
| xnu-201.42.3 | — | -59 |
| xnu-201.5 | — | -59 |
| xnu-2050.22.13 | — | -60 |
| xnu-2050.24.15 | — | -60 |
| xnu-2050.48.11 | — | -60 |
| xnu-2050.7.9 | — | -60 |
| xnu-2050.9.2 | — | -60 |
| xnu-2422.1.72 | — | -60 |
| xnu-2422.100.13 | — | -60 |
| xnu-2422.110.17 | — | -60 |
| xnu-2422.90.20 | — | -60 |
| xnu-2782.1.97 | — | -60 |
| xnu-2782.10.72 | — | -60 |
| xnu-2782.20.48 | — | -60 |
| xnu-2782.30.5 | — | -60 |
| xnu-3247.10.11 | — | -60 |
| xnu-3248.20.55 | — | -60 |
| xnu-3248.30.4 | — | -60 |
| xnu-3248.40.184 | — | -60 |
| xnu-3248.50.21 | — | -60 |
| xnu-3248.60.10 | — | -60 |
| xnu-344.12.2 | — | -59 |
| xnu-344.2 | — | -59 |
| xnu-344.21.73 | — | -59 |
| xnu-344.21.74 | — | -59 |
| xnu-344.23 | — | -59 |
| xnu-344.26 | — | -59 |
| xnu-344.32 | — | -59 |
| xnu-344.34 | — | -59 |
| xnu-344.49 | — | -59 |
| xnu-3789.21.4 | — | -60 |
| xnu-3789.31.2 | — | -60 |
| xnu-3789.41.3 | — | -60 |
| xnu-3789.51.2 | — | -60 |
| xnu-3789.60.24 | — | -60 |
| xnu-3789.70.16 | — | -60 |
| xnu-4570.20.62 | — | -60 |
| xnu-4570.31.3 | — | -60 |
| xnu-4570.41.2 | — | -60 |
| xnu-4570.51.1 | — | -60 |
| xnu-4570.61.1 | — | -60 |
| xnu-4570.71.2 | — | -60 |
| xnu-4903.231.4 | — | -60 |
| xnu-4903.241.1 | — | -60 |
| xnu-4903.270.47 | — | -60 |
| xnu-517.11.1 | — | -59 |
| xnu-517.12.7 | — | -59 |
| xnu-517.3.15 | — | -59 |
| xnu-517.3.7 | — | -59 |
| xnu-517.7.21 | — | -59 |
| xnu-517.7.7 | — | -59 |
| xnu-517.9.4 | — | -59 |
| xnu-517.9.5 | — | -59 |
| xnu-6153.101.6 | — | -60 |
| xnu-6153.121.1 | — | -60 |
| xnu-6153.141.1 | — | -60 |
| xnu-6153.41.3 | — | -60 |
| xnu-6153.61.1 | — | -60 |
| xnu-6153.81.5 | — | -60 |
| xnu-7195.101.1 | — | -60 |
| xnu-7195.121.3 | — | -60 |
| xnu-7195.141.2 | — | -60 |
| xnu-7195.60.75 | — | -60 |
| xnu-7195.81.3 | — | -60 |
| xnu-792.1.5 | — | -60 |
| xnu-792.10.96 | — | -60 |
| xnu-792.12.6 | — | -60 |
| xnu-792.13.8 | — | -60 |
| xnu-792.17.14 | — | -60 |
| xnu-792.18.15 | — | -60 |
| xnu-792.2.4 | — | -60 |
| xnu-792.21.3 | — | -60 |
| xnu-792.22.5 | — | -60 |
| xnu-792.24.17 | — | -60 |
| xnu-792.25.20 | — | -60 |
| xnu-792.6.22 | — | -60 |
| xnu-792.6.56 | — | -60 |
| xnu-792.6.61 | — | -60 |
| xnu-792.6.70 | — | -60 |
| xnu-792.6.76 | — | -60 |
| xnu-8019.61.5 | — | -60 |
| xnu-8019.80.24 | — | -60 |
| xnu-8020.101.4 | — | -60 |
| xnu-8020.121.3 | — | -60 |
| xnu-8020.140.41 | — | -60 |
| xnu-8792.61.2 | — | -60 |
| xnu-8792.81.2 | — | -60 |
| xnu-8796.101.5 | — | -60 |
| xnu-8796.121.2 | — | -60 |
| xnu-8796.141.3 | — | -60 |
Notes
swtch is a historical Mach trap used by user-space spinlock implementations to relinquish the CPU when a lock is contended. It returns a boolean indicating whether any other thread was actually run. On modern macOS, prefer os_unfair_lock, dispatch primitives, or thread_switch with a target port; raw swtch is rarely useful and the kernel may treat it as a no-op hint.
Detection
DTrace's mach_trap provider fires on entry/return (mach_trap:::entry with probefunc == "swtch"). It does not surface in Endpoint Security.
Related APIs
swtch_prithread_switchsched_yieldos_unfair_lock_lock