In order to make Windows Vista, with all of it new GUIenhancements, a success, Microsoft knew that it was going to have to figure outsome ingenious ways to squeeze more performance out of the operating system andthe currently available hardware technology. Along the way, they've even helpedto spur a new hardware technology.
To squeeze more performance out of the operating system,Microsoft has endowed Windows Vista with SuperFetch.To squeeze more performance out of the currently available hardware technology,Microsoft added ReadyBoost to Windows Vista. To helpspur new hardware technology, Microsoft added ReadyDrivecapability to the operating system.
In this edition of the Windows Vista Report, I'll take acloser look at SuperFetch and ReadyBoostand explain how they work together to enhance Windows Vista's performance. I'llthen briefly discuss the concept of ReadyDrive as itrelies on technology that is not yet available.
SuperFetch
Of the three performance enhancement technologies, SuperFetch is the only one that comesfully operational right out of the box. And while SuperFetchby itself can enhance the operating system performance, it will jump up to thenext level when used in conjunction with ReadyBoostor ReadyDrive.
The biggest culprit when it comes to slow performance in thecomputer is disk I/O. As the Windows operating system has evolved over theyears we've seen several technologies designed to attempt to mitigate this performancedrain. The most notable of these technologies is virtual memory, which is alsoknown as the swap file of page file. The Windows XP operating system added a newtechnology called Prefetch. And while these technologiesdid indeed do their part to improve performance, there was room forimprovement.
The SuperFetch technology inWindows Vista is that improvement! SuperFetch isessentially a memory management feature designed to enhance Windows Vista'sresponsiveness when loading and switching between applications that you usemost often. Using adaptive techniques, SuperFetchwill constantly reorganize most often used data and applications on the harddisk and intelligently move them to specific locations on the hard disk wherethey can be loaded into memory the fastest.
For those of us who remember using Windows 3.x, the notionof constant data reorganization may bring back memories of an performancestealing annoyance we called disk thrashing, in which the operating systemtried to simultaneously perform all disk I/O operations. However, SuperFetch won't fall victim to that problem as it takesadvantage of an I/O prioritization technology, in which applications are markedas either a low- or high-priority I/O application. With this system SuperFetch will temporarily sideline a low-priority I/Oapplication when a high-priority I/O application takes precedence. Of course,this will greatly improve the performance of those applications marked ashigh-priority I/O.
ReadyBoost
While SuperFetch is designed tomore efficiently manage memory usage, it must still depend on the speed of thehard disk to move data and applications from the cache to RAM. And as we allknow by now, the fact that a hard disk is a device that relies on physicallymoving components makes it inherently slow, regardless of how much hard diskperformance has improved over the last few years.
However, the widespread availability of USB memory stickwith fast access flash memory offered Microsoft an alternative place to workwith SuperFetch's cache. When you insert a USB memorystick into a Windows Vista system you'll see an AutoPlay dialog box like theone shown in Figure A.
Figure A |
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| When you insert a USB memory stick into a Windows Vista system you'll see thisAutoPlay dialog box. |
When you click the button Speed UpMy System Using Windows ReadyBoost, Windows Vistawill initiate a series of tests to determine whether the USB memory stick iscompatible with ReadyBoost. You'll then see the ReadyBoost tab on the disk's properties sheet. If the USBmemory stick isn't compatible, you'll see a message informing you that thedevice doesn't have the required performance characteristics for ReadyBoost. If the memory stick is compatible, you can selectthe Use This Device option to enable ReadyBoost andspecify how much space that you want to make available to SuperFetch,as shown in Figure B.
Figure B |
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| Windows Vista will automatically set aside a recommended amount of spacefor use with SuperFetch. |
(While many of currently available USB memory sticks meetthe compatibility requirements for ReadyBoost--2.5MB/secthroughput for 4K random reads and 1.75MB/sec throughput for 512K random writes--Microsoftis working with vendors and developing a ReadyBoostlogo program for USB memory sticks.)
As you can see, Windows Vista will automatically set asidethe recommended amount of space, but you can use the slider to change theamount of space. In this example, Windows Vista recommended reserving 880MB ofthe 1GB USB memory stick.
Once you click OK, Windows Vista will configure the USBmemory stick for ReadyBoost and immediately copy thecache over to the drive and begin using it. If you access the drive from Computer,you can actually see the cache, as shown in Figure C.
Figure C |
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| Windows Vista immediately copies the cache over to the drive and beginsusing it. |
In order to ensure the safety, integrity, and efficiency ofthe ReadyBoost system, Microsoft has added several safeguards.To begin with, the data on the USB memory stick is automatically encryptedusing the Advanced Encryption Standard - AES 128. Therefore, if you happen toloose the USB memory stick, you won't have to worry about someone easilyaccessing the data. While Windows Vista will actually work from the cache onthe USB memory stick, all the data in the cache is mirrored on the hard disk'scache. Therefore, if you inadvertently remove the USB memory stick while it'sin use by ReadyBoost, the operating system willimmediately fall back to the hard disk's cache and pick up right where it left off.
ReadyDrive
As I mentioned, ReadyDrive is designedto work with technology that's not yet available called a Hybrid Hard Drive(HDD), which is actually the combination of traditional hard disk and flashmemory. In this case, the two technologies function together with the flashmemory working on the frontline intercepting data and then dispatching it tothe hard disk. This improves performance because the flash memory can handlethe immediate I/O requests faster than the hard disk. Then, during periods oninactivity, cache data can be transferred back and forth between flash memory andthe hard disk.
In addition to its performance enhancement features, the HDDtechnology will be a real boon to laptop users since it will decrease powerconsumption and lengthen battery life. In this case, while flash memory will beable to handle the majority of the hard disk related tasks, the hard disk,which is one of the biggest hogs of battery power, can actually spin down to alow power state until needed. In fact, chances are good that the HDD technologywill first show up in new laptops.
Conclusion
Windows Vista's performance enhancing technologies SuperFetch, ReadyBoost, and ReadyDrive offer a real improvement for disk I/O operations.If you have comments or information to share about Windows Vista's SuperFetch, ReadyBoost, and ReadyDrive, please take a moment to drop by the Discussionarea and let us hear.
