CSC 456 Fall 2013/1c wa: Difference between revisions
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Theory: Cache Associativity decreased as cache size became larger because it became too expensive to have to search the cache each time once the cache was too large. | Theory: Cache Associativity decreased as cache size became larger because it became too expensive to have to search the cache each time once the cache was too large. Also, bigger the cache size as a percentage of main memory, the less need for associativity. But while caches and main memory have both grown, main memory size has grown faster in the 2000’s. So when the percentage of cache to main memory goes down associativity needs to increase. | ||
Revision as of 19:25, 24 September 2013
Trends in cache size and organization
Task 1c. Trends in cache size and organization Over the years, caches have grown larger--up to a point, and then L1 caches tended for awhile to decrease in size. Why? In the early 1980s, associativity increased; beginning about 1990, it decreased, and then by about 2000, it was increasing again. Why? When was the first machine with an L2 cache? An L3 cache? How fast were the various levels of caches, and how did this speed compare to main memory? There is a wealth of information to bring to bear on this topic.
Theory: Cache Associativity decreased as cache size became larger because it became too expensive to have to search the cache each time once the cache was too large. Also, bigger the cache size as a percentage of main memory, the less need for associativity. But while caches and main memory have both grown, main memory size has grown faster in the 2000’s. So when the percentage of cache to main memory goes down associativity needs to increase.
The Pentium/Pentium (1995)pro was the first processor to have the l2 cache on the processor chip. Before this, the l2 cache was an option to add on to the motherboard. [1]
Systems to consider in table
Pentium amd Mips sun-microsystems: sparc ibm: power pc DEC: alpha
Penalty <100 when before 2000 after 2000 started to increase to get to main memory < 20 1 level fine <=100 2 level >=200 3 level
miss rate reported, spec benchmarks
L1 & L2 cache
| System | Year | L1 Size (cache) | L1 Speed (cc) | L1 Associativity | L2 Size | L2 Speed | L2 Associativity | L2 On-Chip? | L3 Size | L3 Speed | L3 Associativity | L3 On-Chip? | Main Mem Penalty (cc) | Notes: | |
| Pentium 4 | 10/2000 | 8 KB (trace) | 2 | 4 Way | 256KB | full speed | 8 Way | Yes | None | 4 (Mem controller) | |||||
| Alpha 21064(DEC) | 09/1992 | (8+8) KB | 1 | Direct | 128kb - 16mb | 3-16 cc | Direct | No | 8 cc | ||||||
| UltraSPARC III | ?/2001 | (32+64) KB | 1 | 4 Way | 2-8MB | 2-3 | ? | No | 4 (Mem controller) | ||||||
| Alpha 21064(DEC) | 09/1992 | (8+8) KB | 1 | Direct | 128kb - 16mb | 3-16 cc | Direct | No | 8 cc | ||||||
| UltraSPARC | 06/1995 | (16+16) KB | 1 | 2-Way & Direct | 512KB - 4MB | 1, pipe=3 | Direct | No | N/A | 2-3 | 64-bit w/ Core@200MHz | ||||
| Alpha 21164(DEC) | 01/1995 | (8+8) KB | 1 | Direct | 96 Kb | 2 | 3 way set | Yes | ? | ||||||
| SuperSPARC | ?/1992 | (16+20) KB | ? | 4 & 5 way set | 0 - 2 MB | ? | ? | No | N/A | ? | Used to render Toy Story, Core @ 40MHz, | ||||
| IBM 360/85 | 1968 | 16 - 32 KB | ? | Sector | None | N/A | N/A | N/A | None | N/A | N/A | N/A | ? | First processor with a cache, clock speed 12.5MHz | |
| Intel 80486 | 1989 | 8 KB | ? | 4-way associative | None | N/A | N/A | N/A | None | N/A | N/A | N/A | ? | First processor with a cache, clock speed 12.5MHz | |
| IBM 486 | 1989 | 8 kb | ? | L1 Associativity | 256 kb | no |
References Ref1 Intel Processors First on-board L1 [faculty.washington.edu/lcrum/Archives/TCSS372AS07/Slides04_05.ppt] [1]