Also remove excessive whitespace in _rm_rlock().
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Event Timeline
| sys/kern/kern_rmlock.c | ||
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| 516 | Why not just use critical_enter()/critical_exit() here? Are we in a spot where the pending preemption check in critical_exit() can't be tolerated? | |
| sys/kern/kern_rmlock.c | ||
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| 516 | See the if statement below, preemption check is merged with another one to save a branch. | |
| sys/kern/kern_rmlock.c | ||
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| 516 | Another reason is that critical_enter()/_exit() were historically not inline functions; that changed only in the past few years. So we could certainly use critical_enter() here, but switching to critical_exit() in _rm_rlock() results in worse-looking code: https://reviews.freebsd.org/P540 I suspect it's worth keeping this micro-optimization. I guess we could at least use critical_enter(), but that on its own doesn't represent much of an improvement to me. | |
| sys/kern/kern_rmlock.c | ||
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| 516 | I have to note critical_exit is already suboptimal by having to test for preemption using a different variable. Instead, both preemption and the flag could be in one int (if not short). It does not even have to be per-thread, rather can be moved per-CPU. I don't know how feasible it is outside of amd64 though. | |