Windows XP Remove 20% of QoS speed will really be fast?

There is a long history of QoS articles in various Windows XP optimization articles, which have been circulating since Windows XP was first released. It has also appeared in various optimization articles on Windows XP.

What exactly is this skill?

Let's take a look at one of the optimization techniques.

“ In the "Run" dialog box, type the “gpedit.msc” command to open the “Group Policy" window, and then from “Administrative Templates” find “Network” Project, there is a “QOS Packet Scheduling” item. After expansion, you can see a “Restrict bandwidth reserved” item under the “Settings” column on the right side of the window. Double-click the item to view it. The default bandwidth is 20%, and we only need to change it to “enabled” and change the "bandwidth limit" value to “0%” The usage rate is the highest. ”

Is the fact that Windows XP keeps 20% of the bandwidth and does not use it for us? After changing 20% ​​to 0%, is it really possible to speed up the Internet? The answer is of course no. Let's first look at how Microsoft explains this problem.

The problem with QoS in Microsoft's KB316666 knowledge base is explained as follows:

Like Windows 2000, in Windows XP, programs can also pass the QoS application programming interface (API). ) to take advantage of QoS. All programs can share 100% of the network bandwidth, with the exception of programs that require bandwidth priority. Other programs can also use this "reserved" bandwidth, except for the requestor that is sending data. By default, the program reserves a bandwidth that is up to 20 percent of the basic link speed of each interface on the terminal computer. If the amount of data sent by a program that reserves bandwidth does not completely run out of bandwidth, the unused portion of the reserved bandwidth can be used for other data streams on the same host.

It is clear in Microsoft's KB316666 that many published technical articles and newsgroup articles have repeatedly mentioned that Windows XP usually reserves 20% of the available bandwidth for QoS is wrong.

Let's first define what the true meaning of QoS is. The Chinese meaning of QoS is: the quality of networked services. Specifically, it refers to various communication or program type prioritization techniques applied across the entire network connection. The existence of QoS technology is to obtain better quality of networked services. QoS is a set of service requirements that the network must meet to ensure proper service level data transfer.

The implementation of QoS enables network applications such as IPTV and network music to use network bandwidth most efficiently. Because it ensures that a certain level of assurance has sufficient network resources, it provides a shared service level similar to a private network. It also provides a means of notifying the availability of application resources, allowing applications to modify requests when resources are limited or exhausted. The goal of introducing QoS technology in Windows XP systems is to establish a guaranteed transport system for network communications.

From the above Microsoft's interpretation of QoS, we can see that by modifying the 20% of QoS to 0% in the Group Policy Editor, the goal of optimizing network performance is not achieved. The modified 20% parameter in Group Policy refers to the maximum amount of bandwidth that can be used when the QoS API writer needs to access the network. If we set it to 0%, it means that the application written with the QoS API must not be used. Without competing for limited bandwidth with other applications, the possible consequence is that data that requires priority communication does not get priority. From this point of view, changing 20% ​​of QoS to 0% will not only have no benefit but also cause some real-time network applications to not use network bandwidth effectively. So this so-called optimization technique can be said to be a misleading.