User and System Time in MT programs

User and System Time in MT programs - User and System Time...

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User and System Time in MT programs Command “time” gives User Time = Time spent in user mode System Time = Time spent in Kernel mode Real Time = wall clock time. In a single processor machine User time + system time < Real time Why? Overhead of other programs running in the same machine. Also cpu waits for the I/O to finish.
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User and System Time in MT programs In a multi processor machine User time + system time < N* Real time Where N is the number of processors If your program is using the N processors at 100% then User time + System time = N* Real time. or (User Time+ System time)/Real Time = N
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Types of Computer Systems Parallel Systems Have more than 1 CPU in the same computer SMP – Symmetric Multiprocessing. Each CPU runs a copy of the Operating System A task that takes T seconds to complete may take ideally T/N seconds. However,
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This note was uploaded on 01/30/2012 for the course CS 252 taught by Professor Gustavorodriguez during the Fall '11 term at Purdue.

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User and System Time in MT programs - User and System Time...

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