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Unformatted text preview: ECSE-2660 Computer Architecture, Networks, & Operating Systems, Spring 2001 Page 1 of 2 SOLUTION In-Class Activity #17 3/27/2001 9:14 AM Activity 17.1 (First Hour) 1. Consider a processor with a 400MHz clock, and a hard disk that transfers data in 8-word chunks with a transfer rate of 6.4 MB/sec. a) (15 points) Assume the processor uses polling and that each polling operation (transferring to the polling routine, accessing the device, restarting the user program) takes 500 clock cycles. Assume you poll often enough so that no data is ever lost. What is the fraction of the CPU time consumed by polling? We must poll at the rate = sec / 000 , 200 / 32 sec / 4 . 6 transf transfer byte MB = Cycles per sec for polling = 200,000 x 500 = 10 8 Fraction of the CPU = 10 8 / 400 x 10 6 = 25% Grading: 10 pts for correct method, 5 for any dimensionally correct formula. b) (15 points) Assume that we use interrupt-driven I/O and the overhead for each transfer is 500 clock cycles. What is the fraction of the CPU time consumed if the disk is transferring data 10% of the time? clock cycles....
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This note was uploaded on 04/25/2010 for the course ECSE ecse-2340 taught by Professor Wozny during the Spring '09 term at Rensselaer Polytechnic Institute.
- Spring '09