Created attachment 1111915 [details]
kshscript

The example script, when run as:

$ ./kshscript driver

will run around 5 times slower in rhel6+ when compared
to rhel5 version of ksh.

  A possible workaround is to run as:

VMALLOC_OPTIONS=break ./kshscript driver

to have the same behavior as rhel5 ksh.

  Another solution is to use system malloc, e.g. have
-D_AST_std_malloc=1 in CFLAGS, what will cause it to
make very few mmap calls and run fast as well (but
make VMALLOC_OPTIONS a noop).