Mach trap#-59
svc · mach trap -59
swtch_pri
Yield variant that temporarily depresses the caller's priority while giving up the CPU.
Prototype
kern_return_t swtch_pri(/* 0 args */);Returns: kern_return_t
Version history
| XNU tag | macOS | # |
|---|---|---|
| xnu-123.5 | macOS 10.0 Cheetah | -58 |
| xnu-201 | macOS 10.1 Puma | -58 |
| xnu-344 | macOS 10.2 Jaguar | -58 |
| xnu-517 | macOS 10.3 Panther | -58 |
| xnu-792 | macOS 10.4 Tiger | -59 |
| xnu-1228 | macOS 10.5 Leopard | -59 |
| xnu-1456.1.26 | macOS 10.6 Snow Leopard | -59 |
| xnu-1699.24.8 | macOS 10.7 Lion | -59 |
| xnu-2050.18.24 | macOS 10.8 Mountain Lion | -59 |
| xnu-2422.115.4 | macOS 10.9 Mavericks | -59 |
| xnu-2782.40.9 | macOS 10.10 Yosemite | -59 |
| xnu-3247.1.106 | macOS 10.11 El Capitan | -59 |
| xnu-3789.1.32 | macOS 10.12 Sierra | -59 |
| xnu-4570.1.46 | macOS 10.13 High Sierra | -59 |
| xnu-4903.221.2 | macOS 10.14 Mojave | -59 |
| xnu-6153.11.26 | macOS 10.15 Catalina | -59 |
| xnu-7195.50.7.100.1 | macOS 11.0 Big Sur | -59 |
| xnu-8019.41.5 | macOS 12.0 Monterey | -59 |
| xnu-8792.41.9 | macOS 13.0 Ventura | -59 |
| xnu-10002.1.13 | macOS 14.0 Sonoma | -59 |
| xnu-11215.1.10 | macOS 15.0 Sequoia | -59 |
| xnu-11417.101.15 | macOS 15.4 Sequoia | -59 |
| xnu-12377.1.9 | macOS 26.0 Tahoe | -59 |
| xnu-10002.41.9 | — | -59 |
| xnu-10002.61.3 | — | -59 |
| xnu-10002.81.5 | — | -59 |
| xnu-10063.101.15 | — | -59 |
| xnu-10063.121.3 | — | -59 |
| xnu-10063.141.1 | — | -59 |
| xnu-11215.41.3 | — | -59 |
| xnu-11215.61.5 | — | -59 |
| xnu-11215.81.4 | — | -59 |
| xnu-11417.121.6 | — | -59 |
| xnu-11417.140.69 | — | -59 |
| xnu-1228.0.2 | — | -59 |
| xnu-1228.12.14 | — | -59 |
| xnu-1228.15.4 | — | -59 |
| xnu-1228.3.13 | — | -59 |
| xnu-1228.5.18 | — | -59 |
| xnu-1228.5.20 | — | -59 |
| xnu-1228.7.58 | — | -59 |
| xnu-1228.9.59 | — | -59 |
| xnu-12377.101.15 | — | -59 |
| xnu-12377.41.6 | — | -59 |
| xnu-12377.61.12 | — | -59 |
| xnu-12377.81.4 | — | -59 |
| xnu-124.1 | — | -58 |
| xnu-124.13 | — | -58 |
| xnu-124.7 | — | -58 |
| xnu-1486.2.11 | — | -59 |
| xnu-1504.15.3 | — | -59 |
| xnu-1504.3.12 | — | -59 |
| xnu-1504.7.4 | — | -59 |
| xnu-1504.9.17 | — | -59 |
| xnu-1504.9.26 | — | -59 |
| xnu-1504.9.37 | — | -59 |
| xnu-1699.22.73 | — | -59 |
| xnu-1699.22.81 | — | -59 |
| xnu-1699.24.23 | — | -59 |
| xnu-1699.26.8 | — | -59 |
| xnu-1699.32.7 | — | -59 |
| xnu-201.14 | — | -58 |
| xnu-201.19 | — | -58 |
| xnu-201.19.3 | — | -58 |
| xnu-201.42.3 | — | -58 |
| xnu-201.5 | — | -58 |
| xnu-2050.22.13 | — | -59 |
| xnu-2050.24.15 | — | -59 |
| xnu-2050.48.11 | — | -59 |
| xnu-2050.7.9 | — | -59 |
| xnu-2050.9.2 | — | -59 |
| xnu-2422.1.72 | — | -59 |
| xnu-2422.100.13 | — | -59 |
| xnu-2422.110.17 | — | -59 |
| xnu-2422.90.20 | — | -59 |
| xnu-2782.1.97 | — | -59 |
| xnu-2782.10.72 | — | -59 |
| xnu-2782.20.48 | — | -59 |
| xnu-2782.30.5 | — | -59 |
| xnu-3247.10.11 | — | -59 |
| xnu-3248.20.55 | — | -59 |
| xnu-3248.30.4 | — | -59 |
| xnu-3248.40.184 | — | -59 |
| xnu-3248.50.21 | — | -59 |
| xnu-3248.60.10 | — | -59 |
| xnu-344.12.2 | — | -58 |
| xnu-344.2 | — | -58 |
| xnu-344.21.73 | — | -58 |
| xnu-344.21.74 | — | -58 |
| xnu-344.23 | — | -58 |
| xnu-344.26 | — | -58 |
| xnu-344.32 | — | -58 |
| xnu-344.34 | — | -58 |
| xnu-344.49 | — | -58 |
| xnu-3789.21.4 | — | -59 |
| xnu-3789.31.2 | — | -59 |
| xnu-3789.41.3 | — | -59 |
| xnu-3789.51.2 | — | -59 |
| xnu-3789.60.24 | — | -59 |
| xnu-3789.70.16 | — | -59 |
| xnu-4570.20.62 | — | -59 |
| xnu-4570.31.3 | — | -59 |
| xnu-4570.41.2 | — | -59 |
| xnu-4570.51.1 | — | -59 |
| xnu-4570.61.1 | — | -59 |
| xnu-4570.71.2 | — | -59 |
| xnu-4903.231.4 | — | -59 |
| xnu-4903.241.1 | — | -59 |
| xnu-4903.270.47 | — | -59 |
| xnu-517.11.1 | — | -58 |
| xnu-517.12.7 | — | -58 |
| xnu-517.3.15 | — | -58 |
| xnu-517.3.7 | — | -58 |
| xnu-517.7.21 | — | -58 |
| xnu-517.7.7 | — | -58 |
| xnu-517.9.4 | — | -58 |
| xnu-517.9.5 | — | -58 |
| xnu-6153.101.6 | — | -59 |
| xnu-6153.121.1 | — | -59 |
| xnu-6153.141.1 | — | -59 |
| xnu-6153.41.3 | — | -59 |
| xnu-6153.61.1 | — | -59 |
| xnu-6153.81.5 | — | -59 |
| xnu-7195.101.1 | — | -59 |
| xnu-7195.121.3 | — | -59 |
| xnu-7195.141.2 | — | -59 |
| xnu-7195.60.75 | — | -59 |
| xnu-7195.81.3 | — | -59 |
| xnu-792.1.5 | — | -59 |
| xnu-792.10.96 | — | -59 |
| xnu-792.12.6 | — | -59 |
| xnu-792.13.8 | — | -59 |
| xnu-792.17.14 | — | -59 |
| xnu-792.18.15 | — | -59 |
| xnu-792.2.4 | — | -59 |
| xnu-792.21.3 | — | -59 |
| xnu-792.22.5 | — | -59 |
| xnu-792.24.17 | — | -59 |
| xnu-792.25.20 | — | -59 |
| xnu-792.6.22 | — | -59 |
| xnu-792.6.56 | — | -59 |
| xnu-792.6.61 | — | -59 |
| xnu-792.6.70 | — | -59 |
| xnu-792.6.76 | — | -59 |
| xnu-8019.61.5 | — | -59 |
| xnu-8019.80.24 | — | -59 |
| xnu-8020.101.4 | — | -59 |
| xnu-8020.121.3 | — | -59 |
| xnu-8020.140.41 | — | -59 |
| xnu-8792.61.2 | — | -59 |
| xnu-8792.81.2 | — | -59 |
| xnu-8796.101.5 | — | -59 |
| xnu-8796.121.2 | — | -59 |
| xnu-8796.141.3 | — | -59 |
Notes
swtch_pri takes a priority argument (historically a Mach urgency) and is used by spinlock backoff code to widen the priority gap between the spinner and the lock holder, mitigating priority inversion. Like swtch, it predates the modern QoS/voucher system and is largely supplanted by os_unfair_lock with priority inheritance.
Detection
Observable via DTrace mach_trap provider; not exposed to Endpoint Security or kauth.
Related APIs
swtchthread_switchthread_policy_setos_unfair_lock_lock