> How do you run the test? Do you specify a maximum available size?
I naively assumed that running "make test" from the toplevel would be
clever about finding plausible parameters. However, it runs the bigmem
tests in a minimalistic way, skipping essentially all interesting bits.  

Thanks for the hints on giving the maximal available size explicitly,
which work in principle, but make testing rather slow. Also, if the
encode/decode test are decorated with 
@bigmemtest(minsize=_2G*2+2, memuse=3)
one needs to specify at least -M 15g, otherwise the tests are still
skipped.  No wonder that people do not normally run them...