1.5.1.Transparency. 1.6. SUMMARY. TheGFC may some day be used for flow control, if an agreement on how to do it can be achieved. TheVPI andVCI fields together identify which path and virtual circuit a cell belongs to. Routing tables along the way use this information for routing. These fields are modified at each hop along the path. The purpose of theVPI field is to group together a collection of virtual circuits for the same destination and make it possible for a carrier to reroute all of them without having to examine theVCI field.. 2. Let processes pick random addresses; locate them by broadcasting.. Fig. 2-36. Multicasting in an internetwork causes trouble.. 4. READ: Read data from a file (or other object).. 20. Is optimistic concurrency control more or less restrictive than using time-stamps? Why?. The need for the ability to wake up all the threads, rather than just one, is demonstrated in the reader-writer problem. When a writer finishes, it may choose to wake up pending writers or pending readers. If it chooses readers, it should wake them all up, not just one. Providing primitives for waking up exactly one thread and for waking up all the threads provides the needed flexibility.. [Картинка: any2fbimgloader126]. In many programs, a critical region is located inside a loop. With eager release consistency, on every pass through the loop a release is done, and all the modified
data have to be pushed out to all the processors maintaining copies of them. This algorithm wastes bandwidth and introduces needless delay. With lazy release consistency, at the release nothing is done. At the next acquire, the processor determines that it already has all the data it needs, so no messages are generated here either. The net result is that with lazy release consistency no network traffic is generated at all until another processor does an acquire. Repeated acquire-release pairs done by the same processor in the absence of competition from the outside are free.. 1. An acquire access of a synchronization variable is not allowed to perform with respect to a process until all updates to the guarded shared data have been performed with respect to that process.. [Картинка: any2fbimgloader186]. To make a long story short, the resulting system was disappointing in terms of performance, resource usage, and so on, and the gap between coarse-grained system objects and fine-grained language objects was not bridged. In 1990, the designers started over and designed COOL-2. This system was running a year later. Below we will describe its architecture and implementation.. 9.7.1. Philosophy. 14. Why do distinguished names have to be unique, but not RDNs?.