create 512 mb internal Ramdisk

NTDEV
1

Hello All

i have a problem related to memory allocation …i created 64 mb buffer use ExallocateMemory API …But i increase size upto 100 mb BSD appeared …then i use mmallocatecached memory in this 512 mb buffer is created but the speed is so slow…

i requested to all tell me another API which create 512 buffer or there is no issue of speed mean run fast.

thanks

2

Well of course noncached memory is slower. You could look into
allocating memory out of user mode process space, but that is quite
complicated and not worth the effort for yet another useless ram disk.

Mark Roddy

On Tue, Oct 19, 2010 at 7:34 AM, wrote:
> Hello All
>
> i have a problem related to memory allocation …i created 64 mb buffer use ExallocateMemory API …But i increase size upto 100 mb BSD appeared …then i use mmallocatecached memory in this 512 mb buffer is created but the speed is so slow…
>
> i requested to all tell me another API which create 512 buffer or there is no issue of speed mean run fast.
>
> thanks
>
>
>
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3

Mark Roddy wrote:

Well of course noncached memory is slower. You could look into
allocating memory out of user mode process space, but that is quite
complicated and not worth the effort for yet another useless ram disk.

I actually did some experiments on this for one of our clients several
years ago. I disabled memory caching system wide, and then ran some
system benchmarks. The results were quite revealing: the overall
performance was 50 to 100 times worse with caching disabled.

–
Tim Roberts, xxxxx@probo.com
Providenza & Boekelheide, Inc.

4

> i have a problem related to memory allocation …i created 64 mb buffer use ExallocateMemory

API …But i increase size upto 100 mb BSD appeared

On most pre-Vista OSes, the nonpaged pool is limited to 128MB, at least on some machines.

Use MmAllocatePagesForMdl or the paged pool.

–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com

5

On some systems having big amount of memory you can also check for HighNonPagedPoolCondition to behave accordnly.

See: http://msdn.microsoft.com/en-us/library/ff563847(VS.85).aspx

HTH