Question # 1 An I/O device transfers data at a rate of 10MB/s over a 100MB/sbus.

Question

Question # 1

An I/O device transfers data at a rate of 10MB/s over a 100MB/sbus. The data is transferred in 4KB blocks. If the processoroperates at 500MHz, and it takes a total of 5000 cycles to handleeach DMA request, find the fraction of CPU time handling the datatransfer with and without DMA.

Question # 2

A magnetic disk has an average seek time of 6 ms. The transferrate

is 50 MB/sec. The disk rotates at 10,000 rpm and the controlleroverhead is 0.2 msec. Find the average time to read or write 1024bytes.  

Explanation / Answer

Question # 2 A magnetic disk has an average seek time of 6 ms. The transferrate is 50 MB/sec. The disk rotates at 10,000 rpm and the controlleroverhead is 0.2 msec. Find the average time to read or write 1024bytes. Solution Average Tseek=6ms Average Trot=0.5*60/10,000=3 ms Ttransfer=1KB/50MB=0.02ms Tcontroller=0.2ms The total time taken= Tseek +Trot+ Ttsfr +Tctr =6+3+0.02+0.2 =9.22 ms

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