c:\windows\prefetch ?

[David]

xp pro sp2
anyone know the specifics about the c:\windows\prefetch?

I was using a program that is simply one .exe file (no install necessary, no
registry settings). I later got an updated version of this .exe file and
copied it over the older one I already had. Then I noticed that the version
number reported by going to help -> about within the program was reporting
the older version! really weird. Because of this I did a search for all
occurences of this .exe file on my system and saw that it came up in this
prefetch folder. In this folder there were a few occurences of this exe only
with some letters and a .pf (assuming for 'PreFetch') appended to the name.
This leads me to believe that this is a place for caching programs in memory
so that they can be launched quickly the next time? but it my case its
launching the wrong version of the program. Anyone know any details of this
behavior?

 

[David]

http://blogs.msdn.com/ryanmy/archive/2005/05/25/421882.aspx

explains this. Also raises other questions to me but those are for a
programmers group. It would seem to me (based on running some tests and
seeing what is created in the prefetch folder) that the hash that is used is
only on the the full path information (including filename) but not on the
file itsself. This is probably for performance reasons... however if this is
true then the system is flawed bacause in cases such as mine where you
simply copy over a 'new' updated exe file overwriting an existing file in
same location then the hash will be the same and when you launch the new
program it will use that existing prefetch file and potentially use pages
from the old program. I am guessing that is what happened to me.

certianly don't take this as fact.... its just what I'm thinking. Also, I
assume MS programmers are much smarter than me so I can't imagine they would
not know this... so I'm probably wrong