Re: [isabelle] isabelle build: number of threads



On Wed, 18 Dec 2013, Christian Sternagel wrote:

I started a build where with -v I got

 ISABELLE_BUILD_OPTIONS=""

My processor is an i7-3630QM (4 cores, 8 threads; which are reported as 8 cores in /proc/cpuinfo ). So I would expect that by default 8 threads are used by "isabelle build". However, I get messages like the following

Timing <session-name> (4 threads, 44.314s elapsed time, 158.450s cpu time, 34.924s GC time, factor 3.58) Finished <session-name> (0:00:57 elapsed time, 0:02:56 cpu time, factor 3.08)

Indicating that only 4 threads are used. When I do the same thing on a different machine with an i7-3520M (2 cores, 4 threads) the corresponding messages are also saying "4 threads".

So my question is, how is the number of threads determined when ISASBELLE_BUILD_OPTIONS is empty?

(This thread is still left-over from last year.)

The main input parameter for Isabelle/ML to determine the number of worker threads is the system option "threads". It is used both for batch build and Isabelle/Scala interaction (e.g. Isabelle/jEdit).

In $ISABELLE_HOME_USER/etc/preferences you can see your local persistent preferences, i.e. what you typically edit via Isabelle/jEdit Plugin Options. I guess that you just have threads = "4" there.


	Makarius




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