[Insight-developers] Not Really Parallel Build

[Kevin H. Hobbs]

>
> How did you measure the test execution time?
> Dashboard is reporting the sum of the execution time of all the tests,  
> which is not what we want IMO. You have to divide it by the number of  
> parallel tests.
>
> The time reported by ctest at the end of the execution is OK.
>
>   

Oh dear, I was just reading the times off of the dashboard, but I see
now that for tests this isn't the wall-clock time at all.

The wall-clock time for the parallel tests on bubbles was only about 8
minutes ( read from <ElapsedMinutes> of Test.xml ), which is just
slightly longer than on the other machines. This morning it's down below
the other machines.

> it would be interesting to have the execution time of two ctest run  
> with a different number of parallel tests on bubble, in the same build  
> tree.
> For example, the output of "time -p ctest -j4 -Q; time -p ctest -j8 -Q".

That's easy enough to try.

[kevin at bubbles Insight_Build]$ CTESTCVS=~/kitware/CMake_Build/bin/ctest
[kevin at bubbles Insight_Build]$ time -p $CTESTCVS -Q; time -p $CTESTCVS
-j2 -Q; time -p $CTESTCVS -j4 -Q; time -p $CTESTCVS -j8 -Q; time -p
$CTESTCVS -j16 -Q;


> PS: Dashboard will have some more problems if you use all those hosts  
> with parallel builds and tests for the next dashboard fest ;-)

I think I heard something about a similar machine being kicked out of
the dashboard fest for being too awesome.

Don't worry. The plan is to have these hosts so overloaded with work by
then that they shouldn't be any threat.

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