Here’s an old PC myth that just won̵
How Windows 10’s QoS Packet Scheduler Works
This setting has been around since Windows XP, so this bad Windows tweaking tip has been around for 20 years now.
Windows 10 has a feature called ‘QoS Packet Scheduler’. It can be found in all versions of Windows starting with Windows XP. QoS stands for “Quality of Service”. It is a way of prioritizing certain types of network traffic, which consists of packets.
QoS comes in many forms. You may have a QoS feature on your wireless router or mesh Wi-Fi system. This allows you to prioritize certain types of traffic: for example, you can make sure that all traffic to and from your work (or gaming) PC has high priority. This ensures that your work (or gaming) isn’t slowed down by another device that might be using a lot of your network bandwidth.
In Windows 10, the QoS Packet Scheduler lets the operating system reserve a certain percentage of your connection’s bandwidth for high-priority network tasks.
Which programs use this reserved bandwidth?
Applications running on your computer can use the reserved bandwidth for high-priority network tasks. They just need to tell Windows that certain traffic is a high priority.
With the default setting, Windows guarantees that 20% of your connection’s bandwidth is always available to programs that request it. If your connection is being used to the maximum by a large video game or BitTorrent download, well, too bad for that download process: Windows will prioritize the network traffic with a lower priority and make a high-priority task 20% of your bandwidth. can get connection work with.
The download takes a bit longer, but there is always a fair amount of bandwidth for a high-priority task, such as streaming a video, perhaps.
How QoS Bandwidth Reservation Really Works
The “Reserve Bandwidth Limit” setting of the QoS Packet Scheduler sets a maximum amount of bandwidth on a connection that Windows will reserve for QoS. The keyword here is ‘maximum’.
If no application tells the operating system that they currently need high-priority bandwidth, Windows makes 100% of it available to other applications. If an application uses 5% of your bandwidth for high-priority tasks, Windows makes 95% of it available to other applications.
Windows makes 100% of the bandwidth of your connection available at all times. The myth says that unless you change this option, Windows will only use 80% of your connection’s bandwidth for other applications and leave 20% of it unused, just in case. That myth makes no sense, and it doesn’t work that way.
Why should you change this setting?
According to this Windows tweaking myth that just won’t go away, change any of these settings to increase the amount of bandwidth available for your applications. However, changing the setting won’t really work – lowering it to “0” will just prevent applications with high priority traffic from using this feature to stay ahead of lower priority applications.
This can make the network applications that matter to you less responsive. Do not touch the setting unless you understand it and know what you are doing.
Don’t you believe us? Microsoft’s Raymond Chen wrote about this issue in 2006 on his blog, The Old New Thing, calling it a “placebo setting” that was getting a lot of attention at the time:
“The institution in question determines how much bandwidth can be claimed for high-priority network access. If no program is using QoS, all your bandwidth is available to non-QoS programs. What’s more, even if a QoS reservation is active, if the program that reserved the bandwidth is not actually using it, the bandwidth is available for non-QoS programs. “
Then he says, “So adjust this value what you want, but understand what you are adjusting.”
If you prefer, you can change the bandwidth percentage in the Group Policy Editor at Computer Configuration> Administrative Templates> Network> QoS Packet Scheduler> Limit Bandwidth Limit.
It can also be modified in the Windows registry with a DWORD value called “NonBestEffortLimit” under Computer HKEY_LOCAL_MACHINE SOFTWARE Policies Microsoft Windows Psched.
But I want Windows 10 to use less bandwidth for updates
If you change the “Limit reservable bandwidth” setting, Windows 10 will not use less bandwidth for updates. Windows still uses as much bandwidth for updates as it otherwise would, but those updates can now slow down your higher priority network traffic.
There are other settings in Windows that give you control over this. For example, you can set a download bandwidth limit for Windows Update, or even tell Windows Update not to automatically download updates.
Why does this myth not disappear?
So why is this tip still so widespread on Windows tweaking websites, even in 2021?
We will tell you a not-so-secret secret: there are many low-quality websites. There are many people who write Windows tweaking tips who do not fully understand what they are writing. It’s a great phone game. Once someone writes a tip and posts it online, it kicks off and other people copy it from website to website.
We don’t do that here at How-To Geek. We want you to know how technology really works. We debunk the myths about tweaking Windows. We do not distribute them.