- Christmas Quiz... - 2 Updates
| "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>: Dec 26 01:22PM -0800 Imagine you are on a SPARC in RMO mode, you are programming in assembly language. What memory barrier instruction is the most efficient _and_ correct for use _after_ using an atomic RMW instruction to take exclusive access? Think about locking a mutex... A: MEMBAR #LoadLoad B: MEMBAR #LoadStore | #LoadLoad C: MEMBAR #StoreLoad | #LoadLoad D: MEMBAR #StoreLoad | #StoreStore What about the membar we have to use before atomically unlocking this mutex? A: MEMBAR #LoadLoad B: MEMBAR #StoreLoad | #LoadLoad C: MEMBAR #LoadStore | #StoreStore D: MEMBAR #StoreLoad | #StoreStore |
| "Alf P. Steinbach" <alf.p.steinbach@gmail.com>: Dec 26 11:17PM +0100 On 26 Dec 2022 22:22, Chris M. Thomasson wrote: > B: MEMBAR #StoreLoad | #LoadLoad > C: MEMBAR #LoadStore | #StoreStore > D: MEMBAR #StoreLoad | #StoreStore I really don't have the foggiest idea, but I wish I had! :-o Google tells me that "RMO mode" is relaxed memory order, and I remember that's been mentioned in what I've read about C++ threading. I can understand that being relevant, but "a SPARC"? Anyway, best wishes for the coming new year. Hopefully at the end there will be less war, less crisis, everything better except the climate (which is FUBAR), and with everything better we can be happy no matter what the climate does. Except my old fav idea of saving the polar bears by transporting them to Antarctica, because the penguins -- possible Antarctica food source -- are now an endangered species. But, better. - Alf |
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