Operations in Cache Memory

-
  • The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. 
  • If requested data is contained in the cache (cache hit), this request can be served by simply reading the cache, which is comparatively faster.
  • Otherwise (cache miss), the data has to be recomputed or fetched from its original storage location, which is comparatively slower.
  • To be cost efficient and to enable an efficient use of data, caches are relatively small.
  • References exhibit temporal locality if data is requested again that has been recently requested already.
  • References exhibit spatial locality if data is requested that is physically stored close to data that has been requested already.

Cache operation

  • CPU requests contents of memory location.
  • Check cache for this data.
  • If present, get from cache (fast).
  • If not present, read required block from main memory to cache.
  • Then deliver from cache to CPU.
  • Cache includes tags to identify which block of main memory is in each cache slot.

Definition of Hit and Miss Ratios

Hit ratio

  • Percentage of requests satisfied from cache
  • Given as value between 0 and 1

Miss ratio

  • Percentage of requests not satisfied from cache
  • Equal to 1 minus hit ratio

Comments

Post a Comment

Popular posts from this blog

Pentium microprocessors

-
Image
A 32-bit microprocessor introduced by Intel in 1993. It contains 3.3 million transistors. Since 1993, Intel has developed the Pentium III and more recently the Pentium 4 microprocessors.   Pentium III Pentium III Mainboard Layout Intel builds on the technology it developed with the Pentium II microprocessors.  The Pentium III processor comes with a Synchronized Dynamic Random Access Memory (SDRAM), allowing for an extremely fast transfer of data between the microprocessor and the memory. 70 new instructions, called Streaming SIMD Extensions, enhance multimedia and 3D performance.  Launched February 1999 - Available in speed levels of 450, 500, 550, and 600MHz. 32KB of Level 1 Cache (operating at CPU's full core speed). 512KB of Level 2 Cache (operating at ½ of CPU's core speed). 100 MHz bus speed. The branch prediction/recovery pipeline was doubled to include 10-stages from the P-II.   Pentium IV The next generation of microprocessors from Intel. Pe
Read more

Design and Management of Computer Networks Running Notes

-
Architecture and Design Process Hierarchy and Inter-connectivity Network Supportability ------------------------------------------------------------------------------------------- Service Description pdf Service characteristics pdf Service Levels pdf System Components and network services pdf Service Requests and Requirements pdf Service Offerings pdf Service Matrices pdf Performance Characteristics pdf for running notes Download here ------------------------------------------------------------------------------------------- Types of user requirements pdf Timeliness Interactivity Reliability Presentation Quality Adaptability Security Affordability Functionality Supportability Future growth Requirement Analysis pdf The need for Requirement Analysis User Requirements pdf for running notes Download here -------------------------------------------------------------------------------------------  Applic
Read more

ONE DIMENSIONAL RANDOM VARIABLES: Handwritten notes

-
Properties of probability Distribution Function Expectation Value For the following problem by using Find the distribution function of x? What is the smallest value of x? for which probability P(X<=x)>0.5 for more click here ---------------------------------------------------------------------------------------------------------------- Continues Random Variable           We call the distribution function as probability density function f(x). Properties of probability density function.  click here ---------------------------------------------------------------------------------------------------------------- Moment Generating Function (MGF) Properties Additional property in MGF  for notes click here ---------------------------------------------------------------------------------------------------------------- Bernoulli Trial       For a single trail with only two possible results.  Example: Tossing a coin. p=1/2, q=1/2 p + q = 1 p = q
Read more