Use of TimerCriticalSection= in 386 Enhanced Mode Windows

 Last reviewed: November 21, 1994
Article ID: Q82228
The information in this article applies to:
  • Microsoft Windows operating system 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.

KBCategory: kbnetwork kb3rdparty
KBSubcategory: wfw wfwg win31 winmem
Additional reference words: 3.0 3.0a 3.1 3.00 3.00A 3.10 3.11

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Last reviewed: November 21, 1994
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