Lazy Allocation, Demand Paging, And Overcommit¶
Lazy Allocation, And Overcommit¶
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Memory Access, And Allocation¶
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Finish: Setup Mapping, Kick Process Loose¶
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Further Notes: TLB Misses, Memory Performance¶
TLB misses not only occur when a mapping is unpopulated
TLB thrashing
TLB is of limited size ⟶ cannot contain all possible address mappings of a process
⟶ Needs occasional updates from OS’s page tables
Programmer’s responsibility (see Optimizations: Memory Optimizations)
Paging/swapping
The OS might have paged out memory to swap (running low on total memory?)
Technically, mapping is not unpopulated
Effect is even worse: guaranteed disk IO
Further Notes: Realtime¶
Lazy allocation is not generally wanted in realtime situations
Allocations must be done up-front
Program itself (code and data) is loaded on-demand ⟶ bad luck if a new code branch is taken at the wrong time
Stack memory is dynamically allocated
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