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12
content/notes/23-IO-systems.md
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@ -4,6 +4,9 @@ aliases:
tags: tags:
- cosc204 - cosc204
- lecture - lecture
sr-due: 2022-11-04
sr-interval: 3
sr-ease: 250
--- ---
interactive between device drivers and IO devices interactive between device drivers and IO devices
@ -49,8 +52,15 @@ Direct memory access
IO performance IO performance
- reduce context switches - reduce context switches
- reduce data copies in memory (normamly two: user mem) - reduce data copies in memory (normamly two: user memory, device/kernel memory): can mmap to share memory
- reduce number of interrupts (e.g., using polling) - reduce number of interrupts (e.g., using polling)
- it data is coming more frequently polling may be faster than interrupts
- increase concurrency (e.g., DMA) - increase concurrency (e.g., DMA)
- move data processing to hardware (e.g., network interface card) - move data processing to hardware (e.g., network interface card)
- balance CPU, memory system, bus, IO performance - balance CPU, memory system, bus, IO performance
Zero-copy
- avoid memory copy in IO data transfer
- use dynamic mmap
- copy data from deice directly to user spce e.g., remote direct memory access RDMA
- pass packet buffer pointers between layers of TCP/IP protocol

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content/notes/cosc-204.md
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@ -53,7 +53,7 @@ tags:
- [20-sync-deadlock](notes/20-sync-deadlock.md) - [20-sync-deadlock](notes/20-sync-deadlock.md)
- [21-memory-management](notes/21-memory-management.md) - [21-memory-management](notes/21-memory-management.md)
- [22-virtual-memory](notes/22-virtual-memory.md) - [22-virtual-memory](notes/22-virtual-memory.md)
-[23-IO-systems](notes/23-IO-systems.md)
# Archive # Archive