CSC 456 Fall 2013/1c wa

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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.

To-Do:
find first L3 and fill in
order the list by year
analyze: average cc speed for a given level, main mem cc speed evolution


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
K6-III 1999 32 kib 256 kib yes 1 mb yes


References Ref1 Intel Processors First on-board L1 [faculty.washington.edu/lcrum/Archives/TCSS372AS07/Slides04_05.ppt‎] [1]

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