Process map and fork problems

Achim Gratz Stromeko@NexGo.DE
Wed Apr 20 11:56:00 GMT 2016


Corinna Vinschen <corinna-cygwin <at> cygwin.com> writes:
> > I think all the affected machines have 4GB memory installed, but the
> > option may not have been default when they were installed.
> 
> They never are default.  Default is 2 Gigs application VM, 2 Gigs
> kernel̇ memory space.  Specifying /3Gb means 3 Gigs application VM
> vs. 1 Gig kernel̇ memory space.  That's not always a good thing
> since it could lead to kernel memory pool exhaustion.

I meant "not default in the base install image provided by corporate IT". 
I'll have to ask if they have some special procedure to switch it on.

> > With /3GB you mean 4GT (aka PAE), right?  And 32bit is without PAE?
> 
> No, PAE works differently, using different calls.  I'm talking abut
> the normal 32 bit address space of a 32 bit CPU.

Hmm.  Microsoft's 4GT documentation makes you believe that /3GB and PAE is
always coupled, though.  But then even non-/3GB might laready use some PAE
facilities anyway.  But I guess it's not important.

> It can only know its own heap.  But keep in mind that the heap can
> be differently sized in different applications.  The heap only *starts*
> as a 384Meg heap, it could easly grow in big apps (gcc, emacs, ...)
> when calling sbrk.

So it can grow only so much until it runs into the first loaded DLL above? 
Or does it fragment into yet unused areas then?


Regards,
Achim.


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