PVM & Linux

[Christos Ricudis]

Hello Linux-greek-users!

  On 20 Apr 99, Linux-greek-users wrote to All with subject "PVM & Linux":

 L> Eksakoloy6w na mhn katalavainw ena pragma. Egw exw mia X efarmogh
 L> poy trexei ayth th stigmh se mia Unix mhxanh. An ayth thn efarmogh
 L> thn metaferw se ena perivallon PVM me polla PC's, thn kanw recompile,

E, den einai kai toso eykolo. Allages sto programma 8a xreiasteis
opwsdhpote.

Basika yparxoyn dyo "kyriarxa" montela parallhlismoy - to Shared Memory model
kai to Massive Parallel Processing model. To prwto xrhsimopoiei kernel-
assisted threads gia concurrent processing, shared memory gia data
distribution, kai semaphores gia synchronization.

Ta 8etika toy stoixeia einai oti einai arketa eykolo sthn syllhpsh kai sthn
ylopoihsh - se ba8mo poy yparxoyn compilers poy kanoyn monoi toys kapoioy 
eidous "parallhlismo" sta loops xwris parembash toy programmatisth - kai exei 
mikro latency. Ta arnhtika stoixeia toy Shared Memory model einai oti exei 
poly periorismeno scalability - douleyei mono se SMP arxitektonikes, oi 
opoies exoyn synh8ws problhma me bus bottlenecks kai periorismeno memory 
bandwidth, ta opoia periorizoyn ta perissotera SMP designs se kapoy metaksy 
16 kai 32 epeksergastwn. 

To Massive Parallel Processing model (sto opoio sygkatalegontai beowulfs, 
PVMs, MPIs ktl ktl) synistatai apo polla processing modules (poy mporei 
na einai apo proprietary processing modules me CPU kai mnhmh h apla 
synh8ismena workstations h PCia) diasyndedemena me ena interconnection 
network. 

To pleonekthma toy einai oti exei para poly kalo scalability an efarmostei 
swsta - sthn taksh twn xiliadwn processing modules. To meionekthma einai 
oti apaitei sobarh douleia apo pleyra programmatismoy, mia poy olo to 
distribution twn dedomenwn, o parallhlismos, to synchronization ktl ktl 
prepei na ginoyn me to myalo kai to xeri, kai prepei epishs na diasfalistei 
oti to inter-CPU communication 8a krath8ei se oso to dynaton xamhlotera 
epipeda, mia poy to typiko interconnection network enos MPP einai merikes 
takseis mege8ous pio "mikro" kai argo apo to typiko SMP bus. Mh stenaxwriesai, 
den einai toso megalh manoura oso akougetai. EINAI AKOMA MEGALYTERH :>. 

Twra teleytaia exoyn arxisei na emfanizontai diafores arxitektonikes poy
prospa8oyn na syndiasoyn thn eyeliksia kai to scalability toy MPP - me
commodity hardware - kai thn eyxrhstia kai aplothta toy SMP. An endiaferesai
psakse sto WWW gia toys orous NUMA kai DIPC (einai entelws diaforetika pragmata
- to prwto einai arxitektonikh kai to deytero einai programmataki, alla 8a soy
dwsoyn mia geysh toy pros ta poy kineitai h ereyna sto parallel software
engineering...)

--
Christos Ricudis
Prof:    So the American government went to IBM to come up with a data
         encryption standard and they came up with ...
Student: EBCDIC!
--
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