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109年 - 109國立臺灣大學_碩士班招生考試_電機工程研究所丙組:計算機結構與作業系統(A)#105855

科目：台大◆電機◆計算機結構與作業系統(A) | 年份：109年 | 選擇題數：0 | 申論題數：57

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所屬科目：台大◆電機◆計算機結構與作業系統(A)

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申論題 (57)

(a) After granting the request (2,0,0) by P1, the system is still safe.
(b) After granting the request (0,3,2) by P2, the system is still safe.
(a) After granting the request (0,4, 1) by P2, the system becomes unsafe.
(b) After granting the request (1,0,0) by P3, the system becomes unsafe.
(c) After granting the request (0,0,2) by P4, the system becomes unsafe.
(a) Line (3) is incorrect!
(b) Line (7) is incorrect!
(c) Line (10) is incorrect!
(a) The solution relies on OS or hardware support for the max operation in line (3).
(b) The solution is incorrect for distributed implementation across internet.
(c) The entry section complexity is O(3n+2) queries to peer processes.
(a) RAID 1 consists of exact copies of the same data on two or more disks.
(b) RAID 2 uses block-level stripe data.
(c) RAID 2 uses parity bit for error detection.
(a) RAID 3 uses byte-level striping with a dedicated parity disk.
(b) RAID 4 consists of bit-level striping with a dedicated parity disk.
(c) RAID 5 consists of bit-level striping with distributed parity.
(a) If the process is allocated 4 frames, the LRU algorithm incurs 10 page faults.
(b) If the process is allocated 6 frames, the optimal algorithm incurs 8 page faults.
(c) If the process is allocated 5 frames, the FIFO algorithm incurs 13 page faults.
(a) If the process is allocated 4 frames, the reference-bit algorithm incurs 15 page faults.   Assume that we start searching from the frame next to the frame with the last brought in page.   If the page last brought in is in the last frame, then we start searching from the first frame.

(b) If the process is allocated 5 frames, the 61e656ae50551.jpg-chance algorithm incurs 14 page faults.  Assume that we start searching from the frame next to the fame with the last brought in page.    If the page last brought in is in the last frame, then we start searching from the first frame.
(c) If the process is allocated 6 frames, the LFU counting algorithm incurs 10 page faults.   Assume that we start searching from the frame next to the frame with the last brought in page.   If the page last brought in is in the last frame, then we start searching from the first frame.
(a) Root is the first process created in system booting.
(b) Daemon is a program running as a background process.
(c) A sysV-style init process can switch between different runlevels.
(a) The init process automatically adopts all orphaned processes.
(b) In System V, runlevel 1 is for single user mode.
(c) The /etc/inittab file defines what each configured runlevel does in a given system.
(a) A cooling door for a rack costs $4000 and dissipates 16 KW (into the room; additional cost is required to get it out of the room). The cooling door can cool 223 servers with a P2 processor, an M2 DRAM, and a single D2 hard drive.
(b) You are considering providing fault tolerance with a P2 processor, an M2 DRAM, and seven D1 hard drives running RAID 2. Now 134 systems can be cooled down on a single rack with a single cooler.
(a) A cooling door for a rack costs $6000 and dissipates 16 KW (into the room; additional cost is required to get it out of the room). The servers are all with a P1 processor, an MI DRAM, and two D1 hard drives with RAID 1. In the farm, a single rack can host up to 28 servers.
(b) From part (a), two cooling doors are required for a single rack.
(c) Suppose a cooling door for a rack costs $3500 and dissipates 28KW (into the room; additional cost is required to get it out of the room).The servers are all with a P2 processor, an M1 DRAM, and five D2 hard drives with RAID 6. In the farm, a single rack can host up to 30 servers.
(a) Larger block sizes reduce compulsory misses, increase the miss penalty, and can increase capacity or conflict misses.
(b) Larger cache capacities reduces miss rate but may incur longer hit time and higher cost and power.
(c) Greater associativity reduces conflict misses. Greater associativity can come at the cost of incrcased hit time.
(a) In a multilevel cache system, the first-level cache can be small enough to match a fast clock cycle time, yet the second-level (or third-level) cache can be large enough to capture many accesses that would go to main memory.
(b) Most proces ssors give cache write misses priority over read misses to reduce miss penalty.
(c) A common optimization is to use the page offset to index the cache in order to remove the translation lookaside buffer (TLB) access from the critical path.
(a) Performance can be improved by renaming register R1 in instruction [1], [2], and [3].
(b) Performance can be improved by renaming register R4 in instruction [5] and [6].
(c) Suppose the register-renamed version of the above code is resident in the RS in clock cycle N, with latencies LW = +4, SW = +1, ADDI=+0, SUB=+0, and BNZ=+2. The number of clock cycles taken by the code sequence is 14.
(a) Suppose that the RS is empty and the front end (decoder/register-renamer) will continue to supply two new instructions per clock cyclc. In cycle 0, the first two register-renamed instructions of this sequence appear in the RS. Assume it takes one clock cycle to dispatch any op in addition to the functional unit latencies. Then 9 clock cycles are required in the first iteration of this code sequence.
(b) Adding another ALU can save two clock cycles.
(c) Adding another LD/ST can save four clock cycles.
(a) The arithmetic intensity of this kernel is 1.
(b) Assuming chaining and a single memory pipeline, there are 4 chimes required.
(a) A code segment with I0 instructions in A, 8 instructions in B, and 5 and instructions in C use 74 cycles.
(b) The CPI of the code in part (a) is 3.
(c) A code segment with 8 instructions in A, 6 instructions in B, and 8 and instructions in C use 82 cycles.
(a) Directory-based protocols in general have better scalability than snooping protocols.
(b) Snooping protocols rely on a shared bus that specifically records which caches have copies of a piece of data so that when a processor modifies its copy in its local cache, updating signals can be sent to the other caches.
(c) Directory-based protocols is usually more complex and inefficient for small-scale systems.
(a) The worst-case remote communication cost when the system is a 4x4 processor grid is 150 ns.
(b) When the system is an 8x8x8 hypercube, the average CPI of the application is smaller than 1.3.
(c) When the system is a 32-node ring, the average CPI of the application is larger than 1.1.