[pypy-dev] exerpt from mail from John Gilmore. How close are we to doing this?

Armin Rigo arigo at tunes.org
Wed Mar 14 10:23:14 CET 2007


Hi,

On Tue, Mar 13, 2007 at 11:32:07PM +0100, Laura Creighton wrote:
> How many pages does Python dirty while it runs?

This could be measured.  It is an area where PyPy has more flexibility
than CPython (what area isn't? :-)  I am not sure so this needs to be
checked, but I believe that if we built a pypy-c that included preloaded
versions of many stdlib modules, we would get a rather bloated
executable, but one which is very close to a memory image of the running
processes.  It means that it would start extremely fast (all modules are
already imported!) and all the pages that come from disk would stay
clean (all prebuilt objects are the same in RAM and on disk).  Multiple
processes would also share all this memory instead of having their own
version of all the function and code objects from all the modules.
Moreover we have no refcounters that dirty all objects all the time.
Boehm might do that, but our custom GC could easily be convinced to
never write into the tag bits of prebuilt objects.


A bientot,

Armin.



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