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PC Operating Systems. Wassn3. cause of thrashing: unfortunate combination of page division (eg program “broken” around loop and an inefficient MMS detect thrashing: not just page faults; by monitoring I/O page queues along with disc utilization
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Wassn3 cause of thrashing: unfortunate combination of page division (eg program “broken” around loop and an inefficient MMS detect thrashing: not just page faults; by monitoring I/O page queues along with disc utilization eliminate thrashing: can’t change MMS dynamically; perhaps by eliminating jobs
request d c b a d c e d c b a e fault * * * * * * * * * frame 1 d d d a a a e e e e e e frame 2 c c c d d d d d b b b frame 3 b b b c c c c c a a Wassn3 6A with 3 page frames
request d c b a d c e d c b a e fault * * * * * * * * * * frame 1 d d d d d d e e e e a a frame 2 c c c c c c d d d d e frame 3 b b b b b b c c c c frame 4 a a a a a a b b b Wassn3 6B with 4 page frames
request a b c d d c b a a b c d fault * * * * * * * * frame 1 a a a d d d d d d d c c frame 2 b b b b b b a a a a d frame 3 c c c c c c c b b b Wassn3 9A - FIFO
request a b c d d c b a a b c d fault * * * * * * frame 1 a a a d d d d a a a a d frame 2 b b b b b b b b b b b frame 3 c c c c c c c c c c Wassn3 9B - LRU
request a b c d d c b a a b c d fault * * * * * * frame 1 a a a a a a a a a a a a frame 2 b b b b b b b b b b b frame 3 c d d c c c c c c d Wassn3 9C - MRU
Sassn3 Simulate the OS memory manager
Sassn3 Simulation analysis…
Sassn3 Output PMT, MMT, success rate
Sassn3 Requests jobX pageY fault? success rate% OS MMT Frm1 Frm2 Frm3 Frm4 1 0 * 0% 1 0 Job 1 PMT 0 in 1 1 in X 2 in X 3 in X 4 in X 1 4 * 0% 1 0 1 4 Job 1 PMT 0 in 1 1 in X 2 in X 3 in X 4 in 2
Sassn3 Input “page requests” JobX requests PageY
Sassn3 Process hand simulate FIFO algorithm…
Sassn3 Simulation synthesis Output, Input, Process
PC Operating Systems Windows System Monitor perfmon