CS232 Mid-term 3 Review1 Review for Mid-term Exam 3Most frequently asked question about any exam: How many questions are there on the exam?3 (on this exam)Other facts about the organization:• Exam takes 50 minutes. Class divided between two rooms: DCL 1320 (last names startingwith A-O) and 1310 (P-Z).• No written references or calculators are allowed.• To receive any partial credit, show your work!2 Things to Study(an incomplete list)1. Caches• Principles of locality, associativity, least rec ently used (LRU).• Basic cache design, multi-level, write-back, write-allocate, etc.• Computing the size of block offset, index and tag fields.• Computing the size of a c ache (amount of data it can hold) and the number of bitsto implement it.• Calculating cache performance and AMAT calculations.• Determining cache performance given patterns of usage.2. Virtual Memory• What is indirection? (Can you give non-VM examples?)• How does VM enable: processes larger than memory? processes to use the sam eaddresses? isolation of one process from another? controlled sharing between pro-cesses?• What is the difference between a virtual address and a physical address?• What is a page table? What is a translation look-aside buffer (TLB)? (How are theyaccessed? what do they contain?)• How does a hierarchical page table work? Why are they used?• What is a page fault? How does the cost of a page fault affect the design of virtualmemory? (e.g., page size, associativity).3. Hard Disks• What are platters, heads, tracks, and sectors?• The four components of an acce ss : seek time, rotational delay, transfer time, andoverhead (and how to compute them).1CS232 Mid-term 3 Review• How random read/write performance differs from the access time of sequential sectorson the same track?4. Error Correcting Codes• Error detection vs. Error correction.• Parity: how it is computed.• Hamming distance: what it is and what degree of protection/correction a givenHamming distance enables?• SECDED.3 Problems1. (a) A program repeatedly performs a three-step process: It reads in a 4-KB block ofdata from disk, does some processing on that data, and then writes out the result asanother 4-KB block elsewhere on the disk. Each block is laid out using contiguoussectors and randomly located on a single track on the disk. Each sector is 512 bytes.The disk rotates at 7200 RPM, has an average seek time of 8 ms, and has a transferrate of 20 MB/sec. the controller overhead is 2 ms. The proce ss ing step takes 20million clock cycles, and the clock rate is 400 MHz. What is the overall speed of thesystem in blocks processed per second?(b) Now suppose the program reads in a 400-KB block of data that is heavily fragmentedand writes back one contiguous block of data to disk. The processing step now takes2 billion clock cycles. What is the overall s pee d of the system in blocks processe dper
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