Feature #1839

Compiling ctools doesn't get faster using 'make -j4'

Added by Mayer Michael over 7 years ago. Updated over 7 years ago.

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Description

The building of GammaLib can be parallelised on several cores using e.g. make -j4. However, this option doesn’t seem to be supported for ctools. Each class is built one by one. Therefore no real acceleration can be seen:

$ cd $CTOOLS
$ make clean
$ time -p make 
 real 91.49
 user 73.82
 sys 11.50
$ make clean
$ time -p make -j4
 real 75.02
 user 76.18
 sys 10.90

Shouldn’t make -j4 be much faster?

Recurrence

No recurrence.

History

#1 Updated by Knödlseder Jürgen over 7 years ago

  • Tracker changed from Bug to Feature
  • Start date deleted (08/08/2016)

This is related to how the ctools code is organised. make -j4 only gets faster if there are several things to compile in the same Makefile. ctools is however not organised that way, but has one Makefile per ctool. For that reason no speed up is obtained.

#2 Updated by Mayer Michael over 7 years ago

Ok I understand. Not sure if this is worth the effort to organise it differently in order to gain a few seconds of speed.

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