Matthias Boehm created SYSTEMML-1946:
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Summary: Incorrect operation parallelism w/ constrained parfor
optimizer and specified k
Key: SYSTEMML-1946
URL: https://issues.apache.org/jira/browse/SYSTEMML-1946
Project: SystemML
Issue Type: Bug
Reporter: Matthias Boehm
When fixing the parfor degree of parallelism with
{code}
parfor(i in 1:100, opt=CONSTRAINED, par=4, log=DEBUG)
print(sum(X %*% rand(rows=1000, cols=1)));
{code}
the constrained parfor optimizer misses to set the operation parallelism
accordingly, which produces the following plan and thus, potentially large CPU
over-provisioning that hurts performance.
{code}
----------------------------
EXPLAIN OPT TREE (type=ABSTRACT_PLAN, size=6)
----------------------------
--PARFOR, exec=CP, k=4, dp=NONE, tp=FACTORING, rm=LOCAL_MEM
----GENERIC (lines 4-4), exec=CP, k=1
------u(print), exec=CP, k=16
------ua(+RC), exec=CP, k=16
------ba(+*), exec=CP, k=16
------dg(rand), exec=CP, k=16
----------------------------
{code}
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