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Windows update and bandwidth. How does it work?

hughlle

Super Moderator
Staff member
Wondering if anyone can offer any insight as to how windows update works regarding internet bandwidth.

Currently downloading a new build, and task manager is telling me that it is using roughly 2mbps. The internet connection is a stable 50mbps (as tested on my phone at the time of the update, and previously on the machine in question).

So despite windows update only using 4% of what is available, on the machine the internet becomes utterly unusable, while it is perfectly fine on every other device. Simple sites take 30-60 seconds to load, something more advanced like engadget etc just time out. How is this possible? Does windows just tell the wifi adaptor that every kb of bandwidth belongs to windows update or something? Is this by design, or a fault, because I can't comprehend the logic in completely crippling a pc just to do an update (which due to their size, and the 2mbps download rate, has been going on all day!).

I'm intrigued, but mostly frustrated.
 

GreyFox7

Super Moderator
Staff member
Does your router have a stats page? I wonder if this info is not accurate. From what I recall Windows update works in spurts more so than a steady trickle.

But how's your CPU usage? They have a broken concept of "background" processing also.
 
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hughlle

Super Moderator
Staff member
Router is a basic provider branded affair, so I doubt it.

CPU was absolutely fine. As I say, for 4 hours the internet was totally unusable on this machine, while all other devices in the house were fine. The instant the download completed everything was back to normal. I have had the same issue on my surface pro as well. Windows update always nukes my internet, however this is the first time!e I've checked device manager and seen that it's using a fraction of the available bandwidth, hence !y thought on the os reserving all network bandwidth regardless of the speed at which MS servers can supply the update. Oh, and it wasn't a solid 2mbps, but would fluctuate between about 600kbps and 2mbps every 5 seconds or so.
 

jnjroach

Administrator
Staff member
Windows Update uses the Background Intelligent Transfer Service (BITS) - For its bandwidth calculation:

BITS attempts to use only spare bandwidth. For example, when applications use 80% of the available bandwidth, BITS will use only the remaining 20%. BITS constantly monitors network traffic for any increase or decrease in network traffic and throttles its own transfers to ensure that other foreground applications (such as a web browser) get the bandwidth they need. Note that BITS does not necessarily measure the actual bandwidth. BITS versions 3.0 and up will use Internet Gateway Device counters, if available, to more accurately calculate available bandwidth. Otherwise, BITS will use the speed as reported by the NIC to calculate bandwidth. This can lead to bandwidth calculation errors, for example when a fast network adapter (10 Mbit/s) is connected to the network via a slow link (56 kbit/s).

Background Intelligent Transfer Service - Wikipedia
 
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hughlle

Super Moderator
Staff member
Thanks Jeff. That's how I figured it would work (in far less technical terms :p). Obviously it is not working for me though, and this occurs on different machines with different wireless adapters on different internet connections using different routers and hubs.
 

GreyFox7

Super Moderator
Staff member
Thanks Jeff. That's how I figured it would work (in far less technical terms :p). Obviously it is not working for me though, and this occurs on different machines with different wireless adapters on different internet connections using different routers and hubs.
Your experience isn't unlike others experience.
Whether CPU, Disk, or Network or a mysterious unknown metaphysical factor the user experience during Windows Update is generally atrocious and has been for years. There might be the occasional non-impactful update but it's more the exception. I always try to deliberately run Windows Update and then use another computer while it's running. It's not uncommon for Windows Update to take hours and occasionally half a day or more. My experience based on updating multiple computers for years.
 

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