Data Cache Thrashing
Stream accesses causes data cache thrashing
- Note that data comes into cache, stays for just a short while before being replaced
- Data cache will not help if vector can’t fit entirely in cache
- Data cache becomes ‘polluted’ with stream data; causes data that might benefit from cache to be thrown out
Designers of a recent multimedia processor recognized this problem and included a small on-chip cache (1K) to be used for streaming data
- Main DMEM cache size was 16K
- Bit in page table used to select which cache to be used; had to be identified by programmer/compiler