[isabelle-dev] NEWS: isabelle build -X

[Makarius]

* The Isabelle tool "build" provides new options -X, -k, -x.


This refers to Isabelle/e0d1d9203275.  At the risk of using up all the 
alphabet for options eventually, there is now the possibility to exlude 
session groups systematically.

This is particularly relevant for AFP/662e7aa68008, to save some hours of 
manual testing:

   isabelle build -d '$AFP' -a -X slow


Here are the results for the slow group alone on my modest home machine 
(12 cores Xeon using -j4 and 6 ML threads):

Finished JinjaThreads (0:38:02 elapsed time, 3:00:37 cpu time, factor 4.74)
Finished ConcurrentGC (0:49:40 elapsed time, 2:26:41 cpu time, factor 2.95)
Finished AODV (1:41:31 elapsed time, 8:46:49 cpu time, factor 5.18)

About 10 years ago, tiny sessions like MicroJava required 45min elapsed 
time.  We are a bit better than that today, but there is also a tendency 
of many people sticking to old hardware, and expecting that things are 
still fast.  Moore's Law means that hardware is continously updated by 
cheaper and faster machines.


 	Makarius