Big allocation AND per process memory!

Oct 14, 2005 0 Replies

Hi EveryOne!


0 See [
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] what MS guy is talking about memory allocation , i wonder that they say that process address space can be 4 GB [ 32 bit architecture ] memory with one half for kernel and another for user. Ok! lets say that



you can just use 2 GB with any user application , fine. If i write a kernel mode code which can access user and as well as kernel space then



it should be able to take care of 4 GB. But why Microsoft guys are just



saying NO for big allocations?


It might be possible that lack of addressing flat memory is due to other than OS itself like TLB , HW cache , VM manager architecture etc..


1)


Say Windows 32 bit OS for intel architecture.


0) Kernel space = 2
1) User space = 2


Total process space = 4 GB.


User mode App. = You have just 2 GB to move around , you keep you data,



routines and string for file mapping here.


Kernel mode code = Ok here you can move around 3 GB.


You can see that our system is consuming min 1 GB [PCB , stack etc.] in



both cases. So we can see that system is spoiling 4 GB [ one process] for every four processes;-)


that is what i'm thinking.


Regards



-ali



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