Answer Happy

A Map/Reduce application is running its map phase on several nodes. All nodes but one have completed their share of the map. The remaining map node has produced half its results, but then crashes. Which of the following will happen in a proper Map/Reduce system? The failed node's partial results will be discarded and its data share assigned to another map node. The reduce phase would be performed on the complete shares, then a second Map/Reduce run would be performed to incorporate the results from the share on the failed node. The failed node's partial results will be delivered to the reduce nodes, and the remainder of its data share will be assigned to another map node. All map results would be discarded and the map phase re-performed on the remaining map nodes. The failed node's partial results will be delivered to the reduce nodes and the reduce phase will be performed without results from the remainder of the failed node's data share. O O
What useful property does a test-and-set instruction have for implementing operating system functionality? It supports virtual machine operations It implements a condition variable It runs in privileged mode, and can be used to implement system call functionality It provides atomicity of the examination and alteration of a memory location It properly updates the page table register
Which of the following statements are true of sloppy counters used in multithreaded programs? They typically run faster than precise counters even with a single thread using the counter O They are simpler to implement than precise counters The number of counters required is equal to the number of threads being used Their benefit is to decrease the amount of locking the multithreaded program requires They can be tuned to trade off accuracy vs. speed Question Which of the following tend to be true of device drivers? O They must be available at kernel configuration time Because they encapsulate control of hardware functionality, they can't crash the operating system They are specific to a particular hardware device Device driver code represents a small fraction on total OS code Applications can only use hardware features exposed by the device driver 0