[Bloat] Win10 Updates vs cake

[Rich Brown]

I'm using LEDE 17.01.4 on my Archer C7v2. I have a 7mbps/768kbps ADSL2+ connection through Fairpoint. The modem stats page shows its "attainable rates" (kbps): 13330/1272 and Rates: 8271/1181. My SQM settings are:

Download: 7000 (kbps)
Upload: 925 
Queue Disc: Cake/piece_of_cake.qos
Link Layer: ATM/44 bytes overhead
Advanced Options: default

I have noticed that Win10 updates cause the network connection to become unusable for other services/people, as if I had bufferbloat. But ping times remain stable - they jump from ~20-22 msec unloaded to 40-50 msec.

Experiments I have tried:

- Setting download speed to 5000 makes the connection usable for other people, although the ping times remain about the same (40-50 msec)

- Setting the download speed to 8600 still keeps ping times down, but that really harms other people's performance.

- The link rates (download and upload) seem to track the SQM setting, measured with both YAMon and the built-in real-time graphs.  I get ~6,000 kbps with a 7000 download setting, I got ~3,000kbps at the 5000 setting. I get ~8500 kbps after setting download to 8600.

- This doesn't seem to happen when I'm downloading other kinds of files (I haven't tried torrenting files...) Downloading non-Win10 update files seems to leave the connection in a fairly responsive state.

Any thoughts? What other experiments should I make? Thanks!

Rich