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pipelinemore about pipeline

pipeline

 

  3  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Pipe-line  \Pipe"-line`\,  v.  t. 
  To  convey  by  a  pipe  line  to  furnish  with  a  pipe  line  or  pipe 
  lines. 
 
  From  WordNet  r  1.6  [wn]: 
 
  pipeline 
  n  1:  gossip  spread  by  spoken  communication;  "the  news  of  their 
  affair  was  spread  by  word  of  mouth"  [syn:  {grapevine},  {word 
  of  mouth}] 
  2:  a  pipe  used  to  transport  liquids  or  gases;  "a  pipeline  runs 
  from  the  wells  to  the  seaport"  [syn:  {line}] 
 
  From  The  Free  On-line  Dictionary  of  Computing  (13  Mar  01)  [foldoc]: 
 
  pipeline 
 
    A  sequence  of  {functional  units}  ("stages") 
  which  performs  a  task  in  several  steps,  like  an  assembly  line 
  in  a  factory.  Each  functional  unit  takes  inputs  and  produces 
  outputs  which  are  stored  in  its  output  {buffer}.  One  stage's 
  output  buffer  is  the  next  stage's  input  buffer.  This 
  arrangement  allows  all  the  stages  to  work  in  parallel  thus 
  giving  greater  throughput  than  if  each  input  had  to  pass 
  through  the  whole  pipeline  before  the  next  input  could  enter 
 
  The  costs  are  greater  latency  and  complexity  due  to  the  need 
  to  synchronise  the  stages  in  some  way  so  that  different  inputs 
  do  not  interfere.  The  pipeline  will  only  work  at  full 
  efficiency  if  it  can  be  filled  and  emptied  at  the  same  rate 
  that  it  can  process. 
 
  Pipelines  may  be  synchronous  or  asynchronous.  A  synchronous 
  pipeline  has  a  master  clock  and  each  stage  must  complete  its 
  work  within  one  cycle.  The  minimum  clock  period  is  thus 
  determined  by  the  slowest  stage.  An  asynchronous  pipeline 
  requires  {handshaking}  between  stages  so  that  a  new  output  is 
  not  written  to  the  interstage  buffer  before  the  previous  one 
  has  been  used 
 
  Many  {CPU}s  are  arranged  as  one  or  more  pipelines,  with 
  different  stages  performing  tasks  such  as  fetch  instruction, 
  decode  instruction,  fetch  arguments,  arithmetic  operations, 
  store  results.  For  maximum  performance,  these  rely  on  a 
  continuous  stream  of  instructions  fetched  from  sequential 
  locations  in  memory.  Pipelining  is  often  combined  with 
  {instruction  prefetch}  in  an  attempt  to  keep  the  pipeline 
  busy. 
 
  When  a  {branch}  is  taken  the  contents  of  early  stages  will 
  contain  instructions  from  locations  after  the  branch  which 
  should  not  be  executed.  The  pipeline  then  has  to  be  flushed 
  and  reloaded.  This  is  known  as  a  {pipeline  break}. 
 
  (1996-10-13)




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