w13-one-IO

w13-one-IO - CS211 Computer Architecture Storage and I/O...

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1 Storage and I/O CS211 Computer Architecture Slides borrowed from: Computer Systems: Randal Bryant and David O’Hallaron(CMU sit e -course on architecture) and Operating systems by Silberschatz, et. Al. book resources web site
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2 Disk-based storage in computers z Memory/storage hierarchy z Combining many technologies to balance costs/benefits z Recall the memory hierarchy and virtual memory lectures
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3 Memory/storage hierarchies z Balancing performance with cost z Small memories are fast but expensive z Large memories are slow but cheap z Exploit locality to get the best of both worlds z locality = re-use/nearness of accesses z allows most accesses to use small, fast memory Capacity Performance
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An Example Memory Hierarchy registers on-chip L1 cache (SRAM) main memory (DRAM) local secondary storage (local disks) Larger, slower, and cheaper (per byte) storage devices remote secondary storage (tapes, distributed file systems, Web servers) Local disks hold files retrieved from disks on remote network servers. Main memory holds disk blocks retrieved from local disks. off-chip L2 cache (SRAM) L1 cache holds cache lines retrieved from the L2 cache memory. CPU registers hold words retrieved from L1 cache. L2 cache holds cache lines retrieved from main memory. L0: L1: L2: L3: L4: L5: Smaller, faster, and costlier (per byte) storage devices
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Page Faults A page fault is caused by a reference to a VM word that is not in physical (main) memory z Example: An instruction references a word contained in VP 3, a miss that triggers a page fault exception null null Memory resident page table (DRAM) Physical memory (DRAM) VP 7 VP 4 Virtual memory (disk) Valid 0 1 0 1 0 1 0 1 Physical page number or disk address PTE 0 PTE 7 PP 0 VP 2 VP 1 PP 3 VP 1 VP 2 VP 4 VP 6 Virtual address VP 3 VP 7
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6 Disk-based storage in computers z Memory/storage hierarchy z Combining many technologies to balance costs/benefits z Recall the memory hierarchy and virtual memory lectures z Persistence z Storing data for lengthy periods of time z DRAM/SRAM is “volatile”: contents lost if power lost z Disks are “non-volatile”: contents survive power outages
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This note was uploaded on 03/24/2011 for the course CS 211 taught by Professor Chakraborty during the Spring '08 term at Rutgers.

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w13-one-IO - CS211 Computer Architecture Storage and I/O...

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