CSC/ECE 506 Spring 2010/ch 3 yl: Difference between revisions
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'''for''' (i=1; i<=N; i++) { | '''for''' (i=1; i<=N; i++) { | ||
'''S1:''' temp[i] = b[i] * c[i];} | '''S1:''' temp[i] = b[i] * c[i];} | ||
'''wait(i-1);''' | |||
'''S2''': a[i] = a[i-1] + temp[i];}''' | '''S2''': a[i] = a[i-1] + temp[i];''' | ||
'''post(i);}''' | |||
[[Image:DOACROSS.jpg]] | [[Image:DOACROSS.jpg]] | ||
Revision as of 20:20, 20 February 2010
Supplement to Chapter 3: Support for parallel-programming models. Discuss how DOACROSS, DOPIPE, DOALL, etc. are implemented in packages such as Posix threads, Intel Thread Building Blocks, OpenMP 2.0 and 3.0.
Parallel-programming models
Loop-independent vs. loop-carried dependences
Loop-independent
Loop-carried dependences
DOALL
for i:=2:N-1 do A(i):=[A(i-1) + A(i) + A(i+1)]/3; next i; forall i:=2:N-1 do A(i):=[A(i-1) + A(i) + A(i+1)]/3;
for (i=2; i<=n; i+=2) s: a[i] = a[i-2]; for (i=3; i<=n; i+=2) s: a[i] = a[i-2];
DOACROSS
for (i=1; i<=N; i++) {
S: a[i] = a[i-1] + b[i] * c[i];}
for (i=1; i<=N; i++) {
S1: temp[i] = b[i] * c[i];}
for (i=1; i<=N; i++) {
S2: a[i] = a[i-1] + temp[i];}
post(0);
for (i=1; i<=N; i++) {
S1: temp[i] = b[i] * c[i];}
wait(i-1);
S2: a[i] = a[i-1] + temp[i];
post(i);}
