Saturday, 2 June 2007

ReadyBoost in Vista

The other method, and probably more informative but at the same time more confusing, is to look at the performance counters for the ReadyBoost feature. The performance counters can actually tell how often ReadyBoost is being used during the time you are monitoring them. Therefore this can be a useful feature in determining whether or not ReadyBoost is actually being used by Vista.

To access the performance counters you should follow these steps.

  1. Click on the Start button.

  2. Click on Control Panel menu option. When in the Control Panel , change to classic view by clicking on the Classic View option.

  3. Double-click on the Administrative Tools icon.

  4. Double-click on Reliability and Performance Monitor icon.

  5. In the left menu click on the Performance Monitor under the Monitoring Tools category

  6. In the right pane, click on the green + sign () to add new counters.

  7. Under available counters, scroll down till you see ReadyBoost Cache and double-click on it to expand this category.

  8. Select the ReadyBoost Cache counter that you would like to add by left-clicking on it and then clicking on the Add button. A list of the counters with some information as to what they mean is shown in a table below.

  9. Once you have added all the ReadyBoost Cache counters that you would like to monitor, press the OK button.

The various counters that you selected will now be seen in the Performance Monitor. As time goes on you will see the activity occurring in real time for each of these counters.

Available ReadyBoost Performance Counters
ReadyBoost Counter Name
Bytes cached The total amount of uncompressed data currently stored in the cache. If there is data being stored then you know ReadyBoost is being used by Vista.
Cache reads/sec The number of times Vista reads from the cache per second. If you see a lot of cache reads per second then you know Vista ReadyBoost is working. If this occurs often when using your computer it is advised you invest in more physical memory to further increase performance.
Compression ratio The actual size of the data in the cache divided by the uncompressed size of the data in the cache. (actual size of the data in the cache) / (uncompressed size of the data in the cache)
Hit read bytes/sec The number of bytes read from the cache per second. This is a further indication that the ReadyBoost cache is being used by Vista. If a lot of bytes are being read per second you also know that you need more physical memory to truly increase your performance.
Invalidated update buffer blocks/sec The number of blocks in update buffers invalidated per second.
Invalidated update buffer bytes/sec The number of bytes invalidated in update buffers per second.
No-regions reschedules/sec Writes rescheduled due to the lack of regions per second.
No-update-buffers reschedules/sec Writes rescheduled due to the lack of update buffers per second.
Read-Size-Max IOs bailed/sec The number of I/Os not serviced by the cache because the size is bigger than the maximum read size per second.
Sequential IOs bailed/sec The number of I/Os not serviced by the cache due to sequentiality per second.
Total read bytes/sec The number of bytes read from the volume per second.
Total write bytes/sec The number of bytes written to the volume per second.
Updated buffer read bytes/sec The number of read bytes services from the update buffers per second.

For the most part you really only need to monitor the Bytes cached, Cache reads/sec, Hit read bytes/sec, Total read bytes/sec, and Total write bytes/sec counters to get a good indication of the amount of ReadyBoost activity occurring on your computer.


ReadyBoost is a powerful feature that allows you to increase performance on your computer in a cheap and easy manner. Though you will not get the same performance increase that you will receive if you actually installed more physical RAM, this method does provide a quick and cheap manner to boost performance. We also know that if you monitor the ReadyBoost activity in the Vista Performance Monitor we can determine if we truly need to install more physical RAM in order to get the best performance benefit.

As always, if you want to learn more about, or discuss with your peers, this guide and other Vista features, then feel free to ask in our Windows Vista forums.

既然你知道了Windows XP的Prefetch技术是如何工作的,你就了解了Windows Vista的SuperFetch技术工作原理的70%。作为Windows XP的Prefetch的下一版本,SuperFetch包括了Prefetch的所有功能并做的更多。

首先,SuperFetch克服了Windows XP的Prefetch中的一个大缺点。正如我前面解释的,Prefetch通过导入大部分由内存中一个应用程序或进程需要的文件或数据,所以可以在需要 时更迅速地访问它们。然而,由于这些文件和数据存在于内存中,所以它们受控制虚拟内存的规则支配。换句话说,当其他应用程序需要访问内存,任何预取的数据 会被移出到硬盘上的页面文件中。当再次需要它时,必须将它从页面文件中移回到内存,这当然抵消了性能增强。

SuperFetch更进一步地保证你获得对性能增强的最有效使用。除了构造我前面提到的映射文件之外,SuperFetch还会构造你使用的应用程序的 描述文件,它包括你在何时使用和使用的频率等信息。然后,SuperFetch将跟踪描述文件中的应用程序并且记录任何预取数据在何时被移出到页面文件 中。SuperFetch将监视引起预取数据被移出到页面文件的应用程序描述文件,并且应用程序一完成,它就将预取数据取回到内存中。所以当你转到访问应 用程序,预取数据将在内存中再次可用而且应用程序会快速响应。

正如我提到的,Windows操作系统会一直利用虚拟内存,无论在系统中安装了多少物理RAM。我还告诉过你SuperFetch中的一种增强方式是尽可 能快地重新将预取数据从虚拟内存页面文件移回到物理内存中以保证性能增强的连续性。然而,由于页面文件存在于比物理内存响应速度慢的硬盘上,所以 SuperFetch会被让硬盘响应其取回操作所花费的时间所阻碍。

为了改进SuperFetch的取回操作,微软决定利用大容量USB 2.0存储棒/闪存驱动器被广泛应用,相对便宜,非常有效-虽然不像物理内存那样有效,但比硬盘要快得多这一事实。当你向Windows Vista系统插入一个USB 2.0存储棒,SuperFetch能够将任何送到虚拟内存的预取数据重定向到USB驱动器,而不是硬盘上。同样的,当需要将数据取回到内存时,取回操作 将更快。
当你将一个USB 2.0存储棒插入到运行Windows Vista的系统中,你将看到类似于图形A中显示的自动运行对话框。

然后将提示你指定你想分配给SuperFetch的存储空间容量如图所示。正如你看到的,Windows Vista将自动留出建议的空间容量,但是你可以使用滑动条增加空间容量。

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