How to use the System File Checker (SFC)(Tips)

Sometimes when you install third party software, it may overwrite important operating system files. This can cause instability - or worse. Windows XP includes a command line tool that you can use if you think this may have happened (for example, if you get a message box warning that there is a problem with a .dll or the system just seems unstable). Here's how to use it:

1. Click Start | Run.
2. In the Run box, type: sfc /scannow Windows will scan all protected Windows files to verify that they are intact and in their original versions. If they're not, corrupt, missing or incorrect files are replaced. You may be prompted to insert your Windows XP installation CD if your Dllcache folder (where Windows keeps a copy of essential system files) has become corrupt or has been deleted.
   
   

How to Customize the Start Menu(Tips)

Is the XP Start menu too "busy" for you? Don't use Outlook Express and want to remove it from its top left "pinned" position on the Start menu, or even better, replace it with the email program you do use? Want to get rid of the links to My Documents and/or other folders on the right side? Want a permanent link to the Administrative Tools on the Start menu? Luckily, you can easily customize it to fit your own needs and preferences. Here's how:

1. Click an empty space on the Start menu and click Properties.
2. Click the General tab.
3. Here you can select whether to include your Web browser and/or e-mail client on the Start menu, and even better, which program to use for each.
4. Click the Advanced tab.
5. Under Start Menu Items, you can select which items to display on the right side of the Start menu, and you can also control how each is displayed. For instance, you can choose to display Control Panel as a menu instead of just a link.
6. On this tab, you can also select whether you want newly installed programs to be highlighted, whether submenus should be opened when you pause on them with your mouse (a feature that can be very annoying), and whether to list your most recently opened documents.

Stop the Desktop Cleanup Wizard from Popping Up(Tips)

By default, every 60 days the XP Desktop Cleanup Wizard pops up and offers to clean up your desktop. What if you like your cluttered, messy desktop? Here's how to make the Wizard leave you alone:

Right click an empty space on the desktop.
Click Properties.
Click the Desktop tab.
Click the Customize Desktop button.
Uncheck the box labeled Run Desktop Cleanup Wizard

Open XP Utilities from the Command Line(Tips)

Are you the command line sort? Would you prefer to type program names into the Run box instead of clicking through menus? Hey, it takes all kinds. Here are the commands to open some of XP's commonly used utilities from the command line:

• Computer Management: compmgmt.msc
• Device Manager: devmgmt.msc
• Disk Defragmenter: dfrg.msc
• Event Viewer: eventvwr.msc
• Local users and groups: lusrmgr.msc
• Local security settings: secpol.msc

Built-in Backup(Tips)

If you're using Windows XP Professional an easy backup solution is just a few clicks away. The built-in Backup utility lets you make copies of files, settings, or everything on your computer. To use the Backup utility:

• Click Start
• Point to All Programs
• Point to Accessories
• Point to System Tools
• Point to Backup

If you use Windows XP Home Edition, you'll have to manually add the Backup utility. To add the utility to Windows XP Home Edition:

1. Insert your Windows XP CD into the drive and, if necessary, double-click the CD icon in My Computer.

2. On the Welcome to Microsoft Windows XP screen, click Perform Additional Tasks.

3. Click Browse this CD.

4. In Windows Explorer, double-click the ValueAdd folder, then Msft, and then Ntbackup.

5. Double-click Ntbackup.msi to install the Backup utility.

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Hide the User Accounts applet from other users(Tips)

Don't want other users to be able to access the User Accounts applet in Control Panel and make changes to user account settings? On your XP Pro computer, you can prevent this by editing the local group policy. Here's how:

1. Click Start | Run.
2. In the Run box, type gpedit.msc. This opens the Group Policy Editor.
3. Expand User Configuration, then Administrative Templates and click Control Panel.
4. Double click "Hide specified Control Panel applets."
5. Click Enabled to check it.
6. Click Show.
7. Click Add.
8. Type nusrmgt.cpl in the box.
9. Click OK.

Note that you can also hide other Control Panel applets. To do so, you need to know their program names. To find the file name of an applet, search for files with the extension .cpl in the System32 folder within the Windows installation folder

Reassign drive letters in XP(Tips)

When you install Windows XP, assigns your drives the lowest letters available (D thru Z) so if you install new drives, the letter of your existing drives won't change. If you already have Windows installed and software installed, here's how to reassign the drive letters.

1. Right-click My Computer.
2. Choose Manage.
3. Click Disk Management.
4. Right-click the drive you want to rename.
5. Select Change Drive Letter or Path.
6. Select your new drive letter

You cannot change a drive letter to a drive letter that already exists, and you cannot change your boot drive.

Clear XP's Page file at Shutdown(Tips)

The Windows page file is a portion of the hard disk used for virtual memory - that is, swapping information in and out of physical memory (RAM) so the applications have more usable memory than is actually installed. The information in the page file is not needed when you shut down, since information in RAo so in Windows XP Pro by performing the following stM is lost when the computer is turned off. The page file can be quite large, so if you want to be sure it's cleared at shutdown to save disk space, you can deps:

1. Click Start | Control Panel | Administrative Tools | Local Security Policy
2. In the Local Security Policy management console, expand Local Policies in the left pane.
3. Click Security Options.
4. In the right pane, scroll down to the policy named "Shutdown: clear virtual memory pagefile." This policy is disabled by default. Right click it and select Properties.
5. Click the Enable option button.

Clear XP's Recent Document List(Tips)

Windows XP remembers your recently opened documents and puts those files in the My Recent Documents menu in the Start menu. This is a useful feature because it allows you to get to stuff you recently opened. Odds are that if you opened a file recently, you're going to open it again! Visiting the My Recent Documents menu speeds up accessing those files you open the most. The problem is other people can see what you've been looking at recently, too! Maybe you opened something recently you don't want anyone to know you've opened. Here's how you clear the list:

1. Right click on an empty area of the taskbar and click Properties
2. In the Taskbar and Start Menu Properties dialog box, click on the Start Menu tab.
3. On the Start Menu tab, click the Customize button. Note that there is a Start menu and a Classic Start Menu option. I'll assume you're using the new Start menu and have the first option selected.
4. After clicking on the Customize button, you'll see the Customize Start Menu dialog box. Click on the Advanced tab.
5. On the Advanced tab, click the Clear List button. This button lies just to the right of the List my most recently opened documents check box. If your computer is like mine, the dialog box will lock up! I hope that your Windows XP computer isn't like mine . Click OK and then click OK again to close all the dialog boxes.

Now when you go to the start menu, you'll see your My Recent Documents folder is gone! Don't worry. It will come back when you start opening documents.

Free Up Space, Control XP's Cache(Tips)

By default, both the Recycle Bin and Internet Explorer's Cache want to consume ridiculous amounts of your hard drive space. Right click on the Recycle Bin, select Properties, and on the Global tab, decide how much space you want the Recycle Bin to consume, either for all drives in your system, or on a per-drive basis. (It's a percentage of the total space. I adjust the slider way to the left, so I'm using "only" a few hundred megs of space for trash.)

Similarly, open Internet Explorer, and select Tools/Internet Options. Under Temporary Internet Files, click the Settings button and select a reasonable size for this cache area. Generally speaking, if you have a fast connection, 5 Mbytes to 10 Mbytes is adequate; 25 Mbytes or so is usually enough with a slower dial-up connection.

Disable Error Reporting(Tips)

By default, XP wants to contact the Microsoft servers to auto-search for patches, downloads, and updates. It also wants to send Microsoft information about any crashes you experience. The former can be an annoyance if the auto-update cycle kicks in at an inopportune time. The latter is a potential security hole, because the crash-reporting information includes a mini-dump of XP's memory contents; it can include snippets of open documents, passwords you've recently typed, and so on.

You can turn off both behaviors by right clicking on My Computer, selecting Properties, and first choosing the Automatic Updates tab. Select either Turn Off or, Notify me.

Customize XP's Taskbar(Tips)

Right click on an empty spot in the Task Bar (the bar next to the Start button). Uncheck Lock the Taskbar. This lets you resize various portions of the taskbar the way you want them. Now, explore the other Taskbar settings to see if any will work for you.

One I always select is Toolbars/Desktop. I place the new Desktop toolbar far to the right on the Taskbar, over by the clock area. Whenever I want access to something on the Desktop that's covered with open windows, I can use this new Desktop toolbar as a shortcut to get to the item on the Desktop without having to close or move any open window.

Improve XP's Folder Views(Tips)

You can easily change the folder view to something more restrained, space-efficient, and useful.

Open My Documents. In the View menu, select Status Bar, List, and Arrange Icons by Name. Next, right click on an empty spot in the My Documents toolbar and select Customize. Choose any of the Available Toolbar Buttons you wish and click Add. Exit the dialog.

Now click to the Tools menu and select Folder Options. Under the View tab, tell XP to show you the full path, to show hidden and system files, not to hide any file extensions, and not to hide protected folders--plus any other settings you want. When you have the folder options set the way you desire, click the "Apply to all folders" button at the top of the dialog. This adjusts all windows opened by Explorer, so they'll inherit the visual choices you made for this one window.

Tune XP's Visual Performance(Tips)

Depending on how you set it up, XP may have reserved a substantial amount of your CPU horsepower for things like animating various desktop elements, placing shadows under menus and cursors, and rounding the upper corners of open windows. In the aggregate, these visual effects can slow down screen-drawing operations significantly. Also, XP may have selected a "color depth" for your video system in excess of what you really need; this, too, can slow down screen operations.

To adjust the color depth, right click anywhere on an empty portion of your desktop and select Properties/Settings. For most normal business users, the Color Quality setting should be set to Medium (16 bit). Higher settings do matter in photo/video editing and similar applications, but for mundane things like Web browsing, E-mail, and word processing, the Medium setting is fully adequate, and it's faster.

To adjust XP's desktop animations and visual effects, right click on My Computer and select Properties/Advanced/Performance Settings. You can choose to activate/deactivate individual items or use the general "best performance/best appearance" buttons. When you've made a change, click Apply, and you'll see the effects almost immediately. (By the way: Selecting Best Performance makes your desktop look very much like the classic desktop in Win98/Win2K.) Experiment until you've found the mix of speed and visual effects that works best for you.

Uninstall Windows Updates(Tips)

Windows Update is a handy tool to ensure that you install critical updates to protect or improve the functionality of your computer, but sometimes an update that is installed may cause problems. What do you do then? Here's how to uninstall update packages and device drivers.

To remove updates, do the following:

1. Click Start, Control Panel and click the Add/Remove Programs icon
2. Select Change or Remove Programs.
3. Locate the update that you want to uninstall, click it to highlight it, and then click Change/Remove.

To uninstall updated drivers, do the following:

1. In Control Panel, click the System applet.
2. Click the Hardware tab, then click Device Manager.
3. Double click the device you need to go back to the previous driver.
4. Click the Driver tab.
5. Click Roll Back Driver.

Another way to undo the changes is to use System Restore, if you made a system restore point before the changes were made

Computer performance Tips.

Enable XP SP2's "Show Updates" Option

One change made by SP2 is the new feature that lets you see the updates that have been installed for your application programs. This is handy for keeping up with the patch status of your programs, but you need to enable it. Here's how:

1. Click Start | Control Panel | Add or Remove Programs.
2. At the top of the Add or Remove Programs window, check the checkbox labeled "Show updates."
3. Scroll to the program for which you want to see updates. The updates will be listed under the program name, along with the date when each update was installed.

Turn Off Windows 98 Logon Screen

If you're the only user on a computer, odds are you don't need a logon screen to appear every time you boot up. Eliminate the need to input your user name and password with these steps.

1. Open Control Panel.
2. Double-click on the Network icon.
3. In the Primary Network Logon, choose Windows Logon.
4. Press OK.
5. In the Control panel link the Passwords applet.
6. Click Change Passwords tab.
7. Press Change Windows Password button.
8. Type in your current password in the Old Password box.
9. Leave both the New Password and Confirm New Password boxes blank.
10. Click OK.
11. Select the User Profile tab and make sure the "All users of this PC use the same preferences and desktop settings" is selected.
12. Click OK.
13. Restart Windows.

This tip doesn't work if you use Windows NT or use profiles.

To free CD-ROM Memory

CD-Rom Cache

If you don't use your CD-ROM often you can free up some of your computer's memory to do other tasks. The CD-ROM has something called cache memory that is set aside for the CD-ROM to use. It helps the CD-ROM run more efficiently if it's frequently in use. To free up some of this memory for other programs to be able to use, follow these instructions:

1. Right-click on My Computer
2. Choose Properties
3. Choose the Performance tab
4. Click the File System button
5. Choose the CD-ROM tab
6. Adjust cache memory down as far as 244.

You'll have to restart your computer for the setting to take effect. If you find your CD-ROM runs poorly, just go back in and raise the cache memory until you find an acceptable level.

To speed up startup time of computer.

MSCONFIG

You can speed up your startup time and make your computer perform better by turning off those little system-level tasks you don't need. Every application that launches at startup uses power and memory that your computer needs for other tasks. Windows provides a program to let you choose what loads at startup. To run MSCONFIG, follow these steps.

1. Go to the Start menu.
2. Choose Run.
3. Type in msconfig.
4. Press OK.

Now that you are in MSCONFIG, go to the Startup Tab. Only uncheck any programs that you are familiar with. Otherwise, you may inadvertently turn something off that you need to compute normally. When you are finished selecting programs, click OK. Next time you start your computer, it should launch faster.
If you turn off a program that you need, simply restore it. Open MSCONFIG and click on the General tab. Selecting the box stating Normal Startup - restores all drivers and software.

Calibrating your computer's battery for best performance

You can calibrate your iBook, PowerBook, MacBook or MacBook Pro computer's lithium ion battery for best performance.

The battery has an internal microprocessor that provides an estimate of the amount of energy in the battery as it charges and discharges. The battery needs to be recalibrated from time to time to keep the onscreen battery time and percent display accurate. With all iBooks and PowerBook G4 computers except the aluminum PowerBook G4 (15-inch Double-Layer SD), you should perform this procedure when you first use your computer and then every few months thereafter.

iBooks and PowerBook G4s other than the PowerBook G4 (15-inch Double-Layer SD)

1. Plug the power adapter in and fully charge your computer's battery until the battery indicator lights turn off and the adapter plug light goes from amber to green, which indicates that the battery is fully charged.
2. Disconnect the power adapter and use your iBook or PowerBook. When your battery gets low, you will see the low battery warning dialog on the screen. Continue to use your computer until it goes to sleep. At that point the battery has been sufficiently drained for calibration.
3. Connect the power adapter and leave it connected until the battery is fully charged again.

You have to fully charge and then discharge your battery only once to calibrate it. After that, you can connect and disconnect the power adapter when the battery is at any charge level.

Tip: When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, any open files could be lost. Therefore, it is important that you find an electrical outlet and connect the adapter before the forced shutdown occurs.

PowerBook G4 (15-inch Double-Layer SD), MacBook (all models), MacBook Pro (all models), and MacBook Pro (17-inch) (all models)

The battery calibration for the PowerBook G4 (15-inch Double-Layer SD) and any model of MacBook or MacBook Pro has been updated because of a new battery released with this computer. With these computers, follow these steps to calibrate your battery:

1. Plug in the power adapter and fully charge your PowerBook's battery until the light ring or LED on the power adapter plug changes to green and the onscreen meter in the menu bar indicates that the battery is fully charged.
2. Allow the battery to rest in the fully charged state for at least two hours. You may use your computer during this time as long as the adapter is plugged in.
3. Disconnect the power adapter with the computer still on and start running the computer off battery power. You may use your computer during this time. When your battery gets low, you will see the low battery warning dialog on the screen.
4. Continue to keep your computer on until it goes to sleep. Save all your work and close all applications when the battery gets very low, before the computer goes to sleep.
5. Turn off the computer or allow it to sleep for five hours or more.
6. Connect the power adapter and leave it connected until the battery is fully charged again.

Tip: When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, with the safe sleep function introduced in the PowerBook G4 (15-inch Double-Layer SD) computers, the computer's memory contents have been saved to the hard drive. When power is restored, the computer returns itself to its pre-sleep state using the safe sleep image on the hard drive.

Computer Laboratory Performance

y requiring operating systems to be ported to run over Xen, machine virtualization can be achieved considerably more efficiently than schemes that rely on trapping faulting instructions or use an interpreter or JIT compiler emulating privileged operating system code. Of course, the downside is you have to do the OS port, but our experience indicates that this usually isn't too time consuming or difficult.

Operating systems running over Xen execute in x86 privilege ring 1 instead of ring 0, which we reserve for Xen. This prevents guest OSes from using the normal privileged instructions to turn on/off interrupts, change page table bases etc. Instead, they must make a 'hypercall' down into Xen to ask the operation to be performed on their behalf. This sounds expensive, but with a properly designed asynchronous interface the hypercalls are relatively infrequent.

Rather than attempting to emulate some existing hardware device, Xen exports specially designed block device and network interface abstractions to guest operating systems, requiring a specially written driver. The advantage of this approach is that guest I/O performance is excellent: we typically get the same performance on Gigabit Ethernet links running over Xen as we do with the native operating system.

As part of evaluation for our SOSP paper, we subjected Linux 2.4.22 to a number of system intensive workloads, then repeated the experiments with the same version of Linux running over Xen, and a number of other virtualization techniques: VMware workstation 3.2 (the latest version of any VMware product which allows the publication of comparative benchmarks), and User Mode Linux (UML) with the skas host patch. The results below show the performance overhead under a number of different scenarios: