Re: Can 64 bit Vista support a 32 bit application with 4 GB?
- From: Tim Roberts <spamtrap@xxxxxxxxxx>
- Date: Sat, 23 Feb 2008 20:46:14 GMT
"Jerome H. Fine" <spamtrap@xxxxxxxxxx> wrote:
However, there is no mention anywhere that I noticed of the possibility
of providing a 32 bit
application program with a full 4 GB of memory under a 64 bit Vista -
assuming that there
is 8 GB of physical memory (or more) available in the first place. Is
this a possibility?
You can get at least 3GB. Part of the address space is still reserved.
This other question is probably even more important. I did some testing
about a year ago
with that 32 bit application. At some point during set up, I requested
1 GB of memory
to be used for a work area. After the test, I was informed that the
test system had only
1 GB of physical memory. So it was obviously not possible to satisfy
the request for 1 GB
of memory from RAM. However, when the request for 1 GB of work area memory
was made, I noticed that it took about 50 to 100 times as long as a
previous request for
100 MBytes of memory. My assumption is that the second request for 1 GB
of memory
was actually backed up with a temporary hard disk file of 1 GB - which
is the default option under WXP.
Yes, the swap file.
Whereas with W98SE that I currently use, the default option is to
reject the request if insufficient physical memory is available - which
is what I require.
No, it most certainly is not. Windows 98 uses virtual memory, exactly like
Windows XP does. You have always been able to request more memory than is
physically present in the machine.
Windows 98 does allow you to run without a swap file, but that's rarely a
good idea.
Why do you "require" this? The operating system has been well tuned over
the last 15 years to make sure that pages that are referenced stay in
memory, and pages that aren't referenced migrate to the swap file. what
makes your application different?
QUESTION: Is there any way to require WXP to set the default for a
memory request to WXP as a reject for a request that can't be satisfied
with actual physical memory?
No. You don't understand what you are asking. Remember that this is a
multitasking operating system. Even an idle XP system is running several
dozen processes, each of which is using various pages of memory. At any
given time, there is typically 0 MB of unused physical memory, and that's
exactly how you should want it. What's the point of having memory, if it
isn't being used?
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
.
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