file mapping thoughts?
hmm at heeg.de
Mon Feb 5 08:05:57 UTC 2001
John M McIntosh wrote:
> I was reading the other day about file mapping (VM related) on
> macintosh OS-9.1 A newly support feature and was wondering about what
> or how it's being used by the Squeak VM on other platforms. I *think*
> I recall some discussion about this topic a while back, or maybe it's
> late and I'm imaging things...
VisualWorks uses this to load (the "permanent" part of) images quickly. For
Smalltalk, it works only well if the image is loaded to the same address it
had when it was saved, because otherwise the pointer relocation dirties all
the mapped pages.
I think that Squeak's memory model should work well with mmapped image files,
especially on platforms where the application's data segment is always at the
same address. This is not true for MacOS up to 9, where all apps are loaded
into one memory arena...
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