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Q177655: Negative Values in Performance Monitor Data

Article: Q177655
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): kbWinNT400sp4fix
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation version 4.0 
- Microsoft Windows NT Server version 4.0 
- Microsoft Windows NT Server version 4.0, Terminal Server Edition 
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IMPORTANT: This article contains information about editing the registry.
Before you edit the registry, make sure you understand how to restore it if
a problem occurs. For information about how to do this, view the "Restoring
the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key"
Help topic in Regedt32.exe.

SYMPTOMS
========

Performance Monitor data exported to a file may include negative values. These
values will correspond to extreme spikes when viewed in Chart view and cannot be
scaled down. The Pages/sec counter of the Memory object is one example. Other
counters will be affected as well.

CAUSE
=====

A condition exists where negative values are not reset to 0. Negative values can
occur when a counter rolls over. The maximum value for any counter is
0xFFFFFFFF.

MORE INFORMATION
================

Values are determined by taking the old value and subtracting it from the new
one. The resulting difference is the data point. The following example uses the
Pages/sec counter.

If the last value was 0x100 and the new value is 0x200, the pages per second is
0x100. If the last value is 0xFFFFFF80 and the ULONG rolls over to 0xC0 (that is
0x140 pages between samples), a negative value occurs (0xC0 - 0xFFFFFF80 =
negative number).

Resetting unreadable or uninterpretable data (such as negative values) can mask
problems in the counters themselves. The registry parameter below determines
whether Performance Monitor logs error and warning events in the Event Viewer
event log when it fails to retrieve data or when it retrieves unreadable or
uninterpretable data (such as negative time). By default, this value entry does
not appear in the registry and Performance Monitor does not log data errors or
notify the user that it has received bad data; it just displays 0 or 100%,
depending on the counter. Perform the following steps to enable logging:

WARNING: Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee that
problems resulting from the incorrect use of Registry Editor can be solved. Use
Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And
Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete
Information in the Registry" and "Edit Registry Data" Help topics in
Regedt32.exe. Note that you should back up the registry before you edit it.

1. Run Registry Editor (Regedt32.exe).

2. Go to the following key:

  HKEY_CURRENT_USER\Software\Microsoft\PerfMon

3. Click Add Value on the Edit menu.

4. Add the following value:

  Value Name: ReportEventsToEventLog
  Data Type: REG_DWORD
  Range: 0 or 1
  Default: 0
  Set the data value to 1.

5. Click OK and then quit Registry Editor.

6. Shut down and restart Windows NT.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or
Windows NT Server 4.0, Terminal Server Edition. For additional information,
please see the following article in the Microsoft Knowledge Base:

  Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack


STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT
Server 4.0, Terminal Server Edition. This problem was first corrected in Windows
NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition
Service Pack 4.


Additional query words: export 4.00 .tsv -1.#I/O
======================================================================
Keywords          : kbWinNT400sp4fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : WinNT:4.0
Hardware          : ALPHA x86
Issue type        : kbbug

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