Julian Elischer wrote: > John Baldwin wrote: > >> >> This is wrong because once you do critical_enter(), you are free to >> assume that you won't do a context switch until you critical_exit(), >> and sx_xlock() would violate that if it blocked on the lock. > > wellllll critical enter doesn't block interupts so it's true if you > don't call > an interrupt as a context switch. > (it doesn't SWITCH contexts but it does step into a different context.) > Yes, interrupts are serviced when a critical section is entered, but ithreads are not run on the same CPU until the critical section is exited. This has been debated quite a bit over the last few years, but I it's a good compromise. This implications just don't seem to be documented well, especially for those who need a protected, uninterruptable context for doing time-critical operations. ScottReceived on Fri May 04 2007 - 19:57:34 UTC
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