On Tue, 26 Feb 2002, John Baldwin wrote: > The critical section stuff currently in current is part of the original > preemption patches I wrote at Usenix last year. They aren't in the tree > because they aren't stable yet. We still have problems on the alpha and > problems with IPI deadlocks on SMP machines that need to be worked out. Since > this API is still very much in flux I'd prefer to keep it simple for now and > not make the code overly complex with optimizations until after we have settled > on the design.
The change is mostly part of the design change needed to un-break fast interrupt handlers. critical_enter() mask not mask hardware interrupts for the same reason than splhigh() must not mask them: there is too much MI code that thinks it is critical and short but really isn't (e.g., everything under spinlocks in -current). Changing cpu_critical_enter() to a null version to prevent spinlocks masking interrupts doesn't work very well because it is used for other things that really do need to mask interrupts. Having 2 levels for cpu_critical_enter() (on that masks normal interrupts and one that masks fast interrupts) would work but I think there are already too many levels of critical_enter()s. Bruce To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
