Describe how polled I/O works and state its disadvantages. Under what conditions is polling a sensible approach? Describe an alternative approach. (You may find it helpful to provide a few lines of psuedo code.) [4 marks] (d) What advantages does direct memory access (DMA) provide? Describe its operation as seen by a device driver in the operating system. (You may find it helpful to a few lines of psuedo code.) [5 marks]A bustling web server could hope to deal with simultaneous solicitations to peruse and update a few common information and could utilize Timestamp Ordering (TSO) to implement separation between simultaneous exchanges. The correctness of the structure and the accuracy of all fields of all nodes are important. Once done, write each of the keys under the cluster in which it is logically stored. [8 marks] (ii) vEB trees store the minimum and maximum key of a subtree in the root node, but do not store the minimum key in any of the descendent clusters. Explain all the reasons why this provides a performance advantage compared with proto-vEB trees. [4 marks] (b) Consider proto-vEB trees. [4 marks] 16 CST.2015.4.1 8 Further Java (a) Describe the operation of wait() and notifyAll(). Ensure that your answer explains when locks are acquired and released. The rate of heat energy flow from a hotter to a cooler object is their temperature difference divided by their insulation resistance. When two fluids are mixed the resultant temperature is the sum of their initial temperatures weighted by their proportions. (a) Give a suitable state vector for a simple, finite-difference, time domain simulation of the drink system. [3 marks] (b) List the initial values and any other parameters that are needed for the simulation. When so applied it should give a value in the IO mthat runs add1 twice and returns the difference between the values read. [4 marks] (d) State what happens when attempting to compile and execute the following Java fragment (explaining the origin of any error messages or exceptions which might arise). Object n = new Integer(42), o = new String("Whoops"); Object [] v; Integer [] w = new Integer[10]; v = w; v[4] = n; v[5] = o; [4 marks] (e) Consider the Java code: Object n = new Integer(42); ArrayList v1; ArrayList v2; ArrayList w = new ArrayList<>(10); Explain any differences in behaviour between assignments v11 = w and v2 = w and also between method calls v1.set(14,n) and v2.set(4,n).