Improving Firefox Responsiveness on macOS

Re:Improving Firefox Responsiveness on macOS by Jarred on Monday October 10, 2022 @03:13PM (#33155330)

Have you looked at `__ulock_wake` versus `os_unfair_lock_with_options`? __ulock_wake is another private darwin API for locking.

From some Zig code:

        // Darwin XNU 7195.50.7.100.1 introduced __ulock_wait2 and migrated code paths (notably pthread_cond_t) towards it:
        // https://github.com/apple/darwin-xnu/commit/d4061fb0260b3ed486147341b72468f836ed6c8f#diff-08f993cc40af475663274687b7c326cc6c3031e0db3ac8de7b24624610616be6
        //
        // This XNU version appears to correspond to 11.0.1:
        // https://kernelshaman.blogspot.com/2021/01/building-xnu-for-macos-big-sur-1101.html
        //
        // ulock_wait() uses 32-bit micro-second timeouts where 0 = INFINITE or no-timeout
        // ulock_wait2() uses 64-bit nano-second timeouts (with the same convention)

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Re:Improving Firefox Responsiveness on macOS by gsvelto on Monday October 10, 2022 @03:47PM (#33155659)

Post author here, `__ulock_wait2` is used under the hood by `os_unfair_lock()`. I considered it but it would have required more scaffolding, especially to support all the versions of macOS we care about. We might use it in the future though.

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Re:Improving Firefox Responsiveness on macOS by cbsmith on Monday October 10, 2022 @03:51PM (#33155702)

Per the documentation (https://github.com/apple/darwin-xnu/blob/main/bsd/kern/sys_u...), it looks like ulock_wait might be one of the XNU primitives that supports os_unfair_lock.

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