Q82228: Use of TimerCriticalSection= in 386 Enhanced Mode Windows

Article: Q82228
Product(s): Microsoft Windows 3.x Retail Product
Version(s): 3.1
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Windows versions 3.0, 3.0a, 3.1, 3.11 
- Microsoft Windows for Workgroups version 3.1 
-------------------------------------------------------------------------------

SUMMARY
=======

In the [386Enh] section of the SYSTEM.INI file, the TimerCriticalSection=
setting can be used in Microsoft Windows running in 386 enhanced mode to prevent
system corruption for some networks and terminate-and-stay-resident (TSR)
programs.

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

The TimerCriticalSection= setting must be entered as follows

     [386Enh]
     TimerCriticalSection=nnnn

where "nnnn" is the amount of time in milliseconds before the critical section is
timed out. For example, a value of 1000 would indicate a 1 second time-out for
the timer critical section.

When this feature is enabled, the virtual machine (VM) assumes ownership of the
critical section before sending a timer interrupt. This prevents timer
interrupts from being serviced in one virtual machine while another virtual
machine is in the critical section (for example, making an MS-DOS call).

The time-out feature allows you to fine-tune the amount of time Windows blocks a
timer interrupt from being serviced in a virtual machine. When a virtual machine
returns from servicing a timer interrupt, the critical section is released and
the time-out is canceled to allow other virtual machines to service timer
interrupts. Typically the time-out will never occur, so it is best to set the
TimerCriticalSection= value to a large value such as 5000. A virtual machine
would then be allowed to "own" all timer interrupts for up to 5 seconds before
other virtual machines would be allowed to run. Because timer interrupt service
routines return very quickly in almost all situations, this will not present a
problem. However, a pop-up program such as Borland's SideKick pops-up on a timer
interrupt and does not return until you pop it down. The time-out is provided to
handle this situation.

TimerCriticalSection=2000 has prevented system corruption on both Banyan and
Novell networks.

Additional query words: 3.0 3.0a 3.1 3.00 3.00A 3.10 3.11

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbWFWSearch kbZNotKeyword3 kbWin300 kbWin300a kbWin310 kbWin311 kbWFW310
Version           : :3.1

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.