Computer Architecture II - Advanced Concepts 3

Computer architecture II Advanced concepts 3 Michael G. Wahl Computer Architecture II Digital Integrated Systems 1 Advanced concepts Parallel Processing Cache - the illusion of a large and fast memory Memory Management – Refresh: Virtual Memory – Example: IBM PowerPC 7450...

Computer architecture II Advanced concepts 3 Michael G. Wahl Computer Architecture II Digital Integrated Systems 1 Advanced concepts Parallel Processing Cache - the illusion of a large and fast memory Memory Management – Refresh: Virtual Memory – Example: IBM PowerPC 7450 – Example: IBM z Instruction sets Computer Architecture II Digital Integrated Systems 2 Tasks of the virtual memory Supports parallel execution of programs / processes – Mapping of an individual virtual address for each program to the physical address space of the installed memory – Protection of program and data against unauthorised access by other programs / processes Supports programs that require more main memory than available. – Based on the locality in time and space – Similar task compared to a cache – Different implementation because of the extremely high difference in access time between memory and large storage media Memory Technology Typical Access Time € / GB (2015) € / GB (2020) SRAM (L1) 0,5 ns DRAM (L4) 10 ns 4-6 4 - 14 Solid State Drive 1 - 5 ms 0.40 0.09 Computer Architecture II Digital Integrated Systems 3 Hard Drive 5 - 9 ms 0.08 0.018 Terminology Basic terms – The memory is logically split into a list of frames. – Addresses in a program: Virtual addresses – Addresses in memory: Physical Addresses – Dynamic mapping of program addresses to memory addresses: Address translation Similarity to cache – Cache block Þ Page – Cache miss Þ Page fault Difference to cache – Access time: DRAM