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Is MaxNumFilters (max NDIS filters) registry value on Windows 8 removed? RRS feed

  • Question

  • Hi,

    I haven't seen MaxNumFilters value under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Network\ registry key on Windows 8 anymore. Is there some changes compared to Windows 7?

    BR, Antti

    Friday, July 6, 2012 6:16 AM

Answers

  • Yes we made some improvements in that department.  Windows Vista and Windows 7 limit the number of NDIS filters that can be installed, since many kernel callbacks are nested through each filter.  If you install too many filters, it's easy to run out of kernel stack space and bugcheck.

    Starting with Windows 8, however, during an NDIS controlpath callout (e.g., status indication), NDIS automatically detects that a callstack is running low on stack space, and expands the stack before calling into the next filter.  The datapath was also reworked to turn recursive calls into iterative calls.  (This is why, if you break into the kernel debugger in the datapath, you no longer see the entire set of filters on the callstack; you'll probably only see the highest filter on the callstack.)

    The net result is that Windows 8 can scale to many more filters, since it is no longer bounded by their cumulative stack consumption.  We have automated tests that go up to 32 filters, I believe.  Therefore, we changed the default value of the installed filter limit to unlimited.  (When the value doesn't exist in the registry, it is interpreted as "unlimited").  "MaxNumFilters" is still read, and would be enforced if you set its value.  In fact, I think this value might be preserved across OS upgrades, so you might find Windows 8 machines "in the wild" with this value still set with a Windows 7 value.

    Monday, December 31, 2012 3:34 PM

All replies

  • Yes, kerro mullekin jos löydät (Junos Pulse)

    Kari

    Friday, December 28, 2012 9:58 PM
  • Yes we made some improvements in that department.  Windows Vista and Windows 7 limit the number of NDIS filters that can be installed, since many kernel callbacks are nested through each filter.  If you install too many filters, it's easy to run out of kernel stack space and bugcheck.

    Starting with Windows 8, however, during an NDIS controlpath callout (e.g., status indication), NDIS automatically detects that a callstack is running low on stack space, and expands the stack before calling into the next filter.  The datapath was also reworked to turn recursive calls into iterative calls.  (This is why, if you break into the kernel debugger in the datapath, you no longer see the entire set of filters on the callstack; you'll probably only see the highest filter on the callstack.)

    The net result is that Windows 8 can scale to many more filters, since it is no longer bounded by their cumulative stack consumption.  We have automated tests that go up to 32 filters, I believe.  Therefore, we changed the default value of the installed filter limit to unlimited.  (When the value doesn't exist in the registry, it is interpreted as "unlimited").  "MaxNumFilters" is still read, and would be enforced if you set its value.  In fact, I think this value might be preserved across OS upgrades, so you might find Windows 8 machines "in the wild" with this value still set with a Windows 7 value.

    Monday, December 31, 2012 3:34 PM
  • I am not able to see the maxnumfilter key in the regedit in my windows 8.1 Pro .Any way i can access it?
    Thursday, October 23, 2014 11:42 AM
  • I am not able to see the maxnumfilter key in the regedit in my windows 8.1 Pro .Any way i can access it?

    if you do a version check, and recognized windows 8 or higher, assume its MAX_INT

    if you have dependencies its you should always check for changes



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    Thursday, October 23, 2014 12:12 PM
  • Okay,so my basic problem here is that after i enable the hyper-v feature in my system it restarts then goes on till 96% then suddenly stops and says unable to install features undoing changes which is quite annoying because i formatted my system specifically to windows 8.1 pro to get the hyper-v feature.Any help on that would appreciated as i am trying to work on developing windows phone apps.Thanks.

    My config:

    Alienware 17

    Intel i7 4700MQ processor

    8GB DDR3

    Windows 8.1 Professional+Ubuntu 14.04;

    WD Hard drive with capacity of 750GB

    And yes hardware virtualization is enabled

    start a new thread, rather than hop in on an unrelated issue


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    Place your rig specifics into your signature like I have, makes it 100x easier!

    Hardcore Games Legendary is the Only Way to Play!
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    Thursday, October 23, 2014 8:51 PM