User-level Distributed Shared Memory

1
User-level Distributed Shared Memory

• Wei Zhang Shu Liu

2
DSM Shared Memory Distributed Memory
3
Problems Solutions
Problems Solutions
Granularity Use 4-Kbyte Page as the unit of sharing
Data location/Mapping Centralized server
Communication MPI (Message Passing Interface)
4
Cont.
Problems Solutions
Memory Coherence in parallelism a each page has one dynamic owner
Memory Coherence in parallelism b multi readers (make copies)
Memory Coherence in parallelism c single writer (only owner can write the page) d lock (synchronize page operation)
5
Design Overview
6
For a read
7
For a write
8
Initial results

• User Level Virtual memory

9
Cont.

• Memory Mapping and Page fault generation (same
  with VM)
• Main DSM Data structure
• pageinfo on server
• page table on nodes
• Communication Functions
• network needs more time than disk
• time of sending a page is more or the less
  than send a byte
• Part of Memory Coherence Model Algorithm

10
Following Steps

• Finish coding (mostly coherence model )
• Evaluation Benchmarks (good and bad results)
• Analyze the results

Good performance
Poor performance