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From: kota on 3 May 2008 08:33
Hi,

I observed that IoAllocateMdl is returning NULL around 30% of the times in
Vista64 but not that much in other OS.
I am allocating the MDL memory for 16MB.
System is AMD 64-bit 2GB RAM and for other OS also, i tested in the same PC.

Do i have modify any settings in vista64-PC to increase the success rate of
IoAllocateMdl?

I have read in an article, when system loads heavily & runs lack of system
pages, it happens, but i tried with SystemPages 0 to not limit of the pages
allocation in regedit, but the response is same.

Thanks,
Kota.
From: Alexander Grigoriev on 3 May 2008 10:08
A single MDL can only cover a bit less than 32MB in x64 system. Such MDL
will take 64 kb of memory. If you allocate a lot of those, and forget to
free them, you might run out of memory.

"kota" <kota(a)discussions.microsoft.com> wrote in message
news:4576CDA7-6494-4FE1-83AC-6C41D29C0610(a)microsoft.com...
> Hi,
>
> I observed that IoAllocateMdl is returning NULL around 30% of the times in
> Vista64 but not that much in other OS.
> I am allocating the MDL memory for 16MB.
> System is AMD 64-bit 2GB RAM and for other OS also, i tested in the same
> PC.
>
> Do i have modify any settings in vista64-PC to increase the success rate
> of
> IoAllocateMdl?
>
> I have read in an article, when system loads heavily & runs lack of system
> pages, it happens, but i tried with SystemPages 0 to not limit of the
> pages
> allocation in regedit, but the response is same.
>
> Thanks,
> Kota.


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