Max. concurrent open files?

NTFSD
1

I’m a new Windows kernel filesystem developer. I would like to find out
if there is a way that I can query the Windows O.S. from my filesystem
code to see how many files can be concurrently opened system-wide.
Is there a way to do this?

Thanks!

2

Because this value is really based upon the available non-paged pool it
isn’t something that could be easily computed. Windows does not use a
table of open files, it dynamically allocates and frees the structures
as they are opened and closed. Thus, there’s no realistic way to obtain
this information.

From a raw numbers perspective, you might be able to open as many as a
half million files or more on a 32-bit Windows system with enough
memory. With a 64-bit system (which has a 128GB maximum non-paged pool
size) that number is vastly larger.

Since you don’t mention why you want this number, it is difficult to
give you guidance. If you are thinking of pre-allocating storage,
however, that wouldn’t be wise. Better to dynamically allocate your
storage as you need it. Keep things in hash tables or AVL trees. Then
you should be able to work with whatever that number is.

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com

Looking forward to seeing you at the next OSR File Systems class in
Boston, MA April 18-21, 2006 (note new date - MS scheduled plugfest the
same week again.)

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of xxxxx@comcast.net
Sent: Friday, February 24, 2006 2:25 PM
To: ntfsd redirect
Subject: [ntfsd] Max. concurrent open files?

I’m a new Windows kernel filesystem developer. I would like to find out
if there is a way that I can query the Windows O.S. from my filesystem
code to see how many files can be concurrently opened system-wide.
Is there a way to do this?

Thanks!

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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