IIS 6 / native memory question

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Scott McFadden - 10 May 2007 20:27 GMT

When I run my 32 bit VC 8 DLL hosted by a managed C++ Winform APP on Win2003
32 bit with 4GB ram it runs fine. When I run the same DLL hosted under a
Managed C++ ASP.NET 2.0 Webservice project (also on Win2003 bit with 4GM
ram, the DLL fails). If i downgrade the box from 4GB of RAM to 2GB of RAM,
the DLL works fine under IIS.

What kind of issue is this? Is this an IIS limitation, a Windows
limitation, or VC limitation?

thanks

ScottM

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Carl Daniel [VC++ MVP] - 10 May 2007 21:56 GMT

> When I run my 32 bit VC 8 DLL hosted by a managed C++ Winform APP on
> Win2003 32 bit with 4GB ram it runs fine. When I run the same DLL hosted
[quoted text clipped - 4 lines]
> What kind of issue is this? Is this an IIS limitation, a Windows
> limitation, or VC limitation?

Impossible to say without a much better description of "the DLL fails".

When the machine is configured with 4GB of memory, is it booting with /3GB?
If so, then it's possible that some address used by the DLL (could be code
or data) has an address above 2Gb, and that such a large address causes a
problem with some logic in the DLL. Such addresses will appear to be
negative numbers if accessed as an integer. (The possibility for such
errors is why there's a special linker flag /LARGEADDRESSAWARE to let a
process access user-mode memory about 2Gb).

-cd

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Scott McFadden - 10 May 2007 22:35 GMT

Oops.. Calloc failures when running on Win2003 with 4GB ram.

So do I need to set the boot.ini flag and link with the /LARGEADDRESSAWARE
option or is one or the other sufficient?

Also, Got any links or info on Application Memory Tuning?

thanks!

ScottM

So I need to set the OS to boot with the /3GB switch and link with the

>> When I run my 32 bit VC 8 DLL hosted by a managed C++ Winform APP on
>> Win2003 32 bit with 4GB ram it runs fine. When I run the same DLL hosted
[quoted text clipped - 16 lines]
>
> -cd

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Carl Daniel [VC++ MVP] - 10 May 2007 23:16 GMT

> Oops.. Calloc failures when running on Win2003 with 4GB ram.

I'm not sure what you mean - are you saying that you're seeing failures from
calloc with large memory? If so, that's certainly a bug - all of the
parameters to calloc are pointers or size_t, which is unsigned.

> So do I need to set the boot.ini flag and link with the /LARGEADDRESSAWARE
> option or is one or the other sufficient?

You have to use both the boot.ini flag and the linker option to actually get
access to >2Gb address space. If you're not doing that, then this probably
isn't your problem.

> Also, Got any links or info on Application Memory Tuning?

Nothing jumps to mind - maybe someone else will have a nice collection of
links.

-cd

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IIS 6 / native memory question

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