Flashcards
Virtual Memory + Parallell
Flashcards do conjunto (10)
- 1What does VM do?It takes program addresses and maps them to RAM addresses.
- 2What problems does VM solve?Mips gives each program 32 bit address space. But what if you don´t have that kind of memory?
- If multiple programs access the same space they can corrupt data - 3What happens when a program tries to load something that is not in RAM?The VM takes the oldest data in RAM and puts it on the disk and updates the Map to point to the right data
- 4How does VM work?-Separate mem spaces;
-VM: what the program sees
-Physical mem: the RAM - 5What is VA and PA?Va: Address that the program uses
Pa: what the hardware uses to talk to RAM. The space is determined of how much Ram is installed - 6How does a program access memory?1. Executes load to specify VA
2. Computer translates VA to PA (in map)
3. If data is not in mem -> load from disk -> update map - 7What can happen if all programs have access to the same 32-bit memory space?• Can crash if less than 4GB of RAM memory in the system
• Can run out of space if we run multiple programs
• Can corrupt other programs’ data - 8How is the virtual addresses mapped?Mapping is Fully Associative! -> need an indirection table, the “Page Table”
- 9How is the VA divided?Memory and virtual memory are divided into frames and pages and the “hot/active” pages are kept
in RAM. Each process does not know if data is in RAM/disk. - 10Calculate parallell perfomanceP = Percentage that can run in parallel (e.g. 90%)
S = # of cores/processors/threads
Speedup =
_______1______
(1−P)+ P/S
Informações
- Descrição
- Dark FlashCards sobre Virtual Memory + Parallell , criado por Emma Tysk em 30-05-2017.
- Criado por
- Emma Tysk
- Visualizações
- 6
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