WebChapter 5 — Large and Fast: Exploiting Memory Hierarchy — 30 Write-Through On data-write hit, could just update the block i n cache But then cache and memory would be inconsistent Write through: also update memory But makes writes take longer e.g., if base CPI = 1, 10% of instructions are stores, write to memory takes 100 cycles Effective CPI = … WebMemory Hierarchy • Memories of different technologies are organized in a hierarchy – The closer to the CPU, the faster and smaller of the memory – The farther from the CPU, the slower and larger of the memory – Data movement from far level to close level are via blocks • 64 bytes from DRAM to cache, and 4KB from disk to DRAM (paging) 5

Chapter 5

WebEECS 112 - Organization of Digital Computers 1 Cache Misses On cache hit, CPU proceeds normally On cache miss Stall the CPU pipeline Fetch block from next level of hierarchy Instruction cache miss Restart instruction fetch After stalling the processor to get the instruction from the memory Data cache miss Complete data access Stall the processor … WebChapter 5 — Large and Fast: Exploiting Memory Hierarchy — 21 Cache Misses On cache hit, CPU proceeds normally On cache miss Stall the CPU pipeline Fetch block from next level of hierarchy Instruction cache miss Restart instruction fetch (re-compute PC) Data cache miss Complete data access choose an account aramark.com

Chapter 5: Large and Fast: Exploiting Memory Hierarchy ppsx

WebMemory Hierarchy Levels Block (aka line): unit of copying May be multiple words If accessed data is present in upper level Hit: access satisfied by upper level Hit ratio: hits/accesses If accessed data is absent Miss: block copied from lower level Time taken: miss penalty Miss ratio: misses/accesses = 1 – hit ratio WebA program repeatedly performs the following three-step process: • read in a 4 KB block of data from disk, • do some processing on that data, and • write out the result as another 4 … WebLevel of memory hierarchy closest to the CPU Direct Mapped Cache Location determined by address Only on choice Index: block addr % blocks in cache Tag The high-order … grease splatter screen walmart