Microsoft KB Archive/310601

= Computer does not enter standby mode if Power Options profile is set to standby after 45 or more minutes =

Article ID: 310601

Article Last Modified on 5/17/2007

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APPLIES TO


 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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This article was previously published under Q310601



SYMPTOMS
After you set the Power Options profile so that your computer enters standby after 45 or more minutes, your computer may not enter standby after 45 or more minutes.



CAUSE
This problem may occur when your computer is running on AC power and the standby time is set to 45 or more minutes. When your computer is running on AC power and is idle for approximately 30 minutes, the Windows XP Idle Task Scheduler service runs the system maintenance tasks, and it resets the System Idle counter while it is running these tasks. If you set the system standby time to 45 or more minutes, the Idle Task Scheduler service starts every 30 minutes, and resets the system idle counter. Because of this, your computer cannot enter standby.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows XP. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

The English version of this fix should have the following file attributes or later:

  Date         Time    Version      Size     File name ---  26-Nov-2001  13:59   5.1.2600.21  250,368  Mstask.dll 26-Nov-2001 13:59   5.1.2600.21    9,728  Mstinit.exe 26-Nov-2001 13:59   5.1.2600.21  158,720  Schedsvc.dll 26-Nov-2001 13:50   5.1.2600.21  155,136  Srsvc.dll



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section. This problem was first corrected in Windows XP Service Pack 1.



MORE INFORMATION
After you apply this hotfix, if the time to standby is more than 15 minutes, standby may be delayed by approximately 15 minutes one time every 3 days. Windows schedules some maintenance tasks when the system is idle and running on AC power. Some idle tasks may cause high CPU and disk usage, which causes delays in entering standby.

Other third-party programs and services may be running during system idle time; these programs and services may cause more than 10 percent CPU and or disk usage. This causes delays in entering standby.

For more information about a related topic, click the following article number to view the article in the Microsoft Knowledge Base:

899975 Windows XP does not enter standby after the exact period that is configured in the Power Options profile



After you apply this hotfix, the System Idle Task Scheduler service is started when your computer is idle for approximately 15 minutes; it schedules the system maintenance task if there is enough time left to complete the task without resetting the System Idle counter.

The System Idle Task Scheduler service monitors for the system to be idle. The system is considered to be idle if for the last 10 minutes:
 * There is no user input.
 * The CPU and disk usage is less than 10 percent.
 * The system is not running on battery power.
 * Presentation programs (such as a slide show or movie playback) are not running.

If all these conditions exist, the service takes a system snapshot for any new tasks that are running on the system every minute for 3 minutes. If no new task is running, the service is ready to schedule any queued tasks. Those can be run when the system is idle. If there is a queued task, the System Idle Task Scheduler service runs the queued task. The System Idle Task Scheduler service does not explicitly change the System Idle counter.

If the scheduled task runs and if it uses more than 10 percent of the CPU and disk usage for a long time, the Kernel-mode System Idle Detection thread determines that the system is not idle and resets the System Idle counter to zero. This causes a delay in entering standby.

The following tasks may be queued and can be scheduled during system idle time:
 * The Disk Layout task:

When you start the computer, this task is queued to run during system idle time. If the System Idle Task Scheduler service schedules this task to run, Windows checks the registry to determine when the Disk Layout task was last run. If the task has not run for the last 3 days, the process continues. Otherwise, the process quits. If the process continues, it determines if there have been many changes in the disk layout from the last time this task was run. It requeues the task after 32 processes are created on the system. To find significant changes in layout, it looks at the files that are in the scenario files in the Windows\Prefetch folder. These scenario files show the files that are used during program startup and computer startup. These are the files to lay out optimally on the disk. If the process continues, it updates the disk layout. This in turn may cause more than 10 percent CPU or disk usage. When usage goes high, the Kernel-mode System Idle Detection thread monitors this change and resets the System Idle counter. This causes delays in entering standby.
 * The System Restore task
 * The Help Services and Data Collection task

Windows XP is designed to automatically complete maintenance tasks to improve performance and reliability. When your computer is on AC power and is idle, Windows XP does not immediately power down your computer. Instead, it provides a chance for system maintenance tasks to run for a few minutes. These system maintenance tasks include disk layout optimization to improve performance (such as for fast boots) and preparing automatic system restore points to increase reliability. These tasks do not delay the powering down (suspend) of your computer for more than 15 minutes. These tasks are not run if your computer is running on battery power. Typically, these tasks are completed the first time your computer is left idle after startup. These tasks help to make sure that your computer maintains its performance and reliability even after long use.

Keywords: kbhotfixserver kbqfe kbbug kbenv kbfix kbsysadmin kbwinxpsp1fix KB310601

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