cs341 Lecture Notes
Spring 2002
Week 14, Monday

For today you should have...

1) worked on hw08

2) solved the Unisex Bathroom problem

3) worked on the practice final exam


Today's topics

1) finish Chapter 16  (notes22.txt)

2) the memory hierarchy

3) practice exam


Memory hierarchy
----------------

page 328

register	500 bytes		1 clock cycle = 1 ns

L1 cache	64 KB			4 ns

L2 cache	256 KB			10 ns

memory		256 MB			60 ns

disk		40 GB			8  ms worst case
					50 us 


Fundamental ideas

1) smaller forms of storage are usually faster

   why is that?



2) as data is used, it migrates toward the processor

   locality of reference rewards cacheing

   What are the two kinds of locality?






   How do caches take advantage of them?








3) the longer it has been since data was used, the more
   likely it has migrated down a level


4) the longer it takes to access storage, the bigger the
   chunks of data get moved around.


What is the difference between a page and a block?








When would you find a page on disk?







When would you find a block in memory?







How can you tell whether the paging system competes with the
disk cache for space in memory?