Speeding up GC

[David S. Miller]

   From: Marc Espie <espie@nerim.net>
   Date: Tue, 4 Jun 2002 18:04:40 +0200

   1/ it may be prohibitively expensive on most OSes that implement it.
   
I don't question this.

   2/ Here, documentation of mprotect says:
   Not all implementations will guarantee protection on a page basis;
   the granularity of protection changes may be as large as an entire re-
   gion.
   
In reality, %99 of UNIX systems do page based granularity because so
many apps need it.  ELF shared libraries are challenging, at best, if
you don't do page based mprotect :-)

It's a moot point because I think the mprotect+SIGSEGV thing is stupid
from a performance standpoint anyways.