Comment 9 for bug 1839237

Can confirm this issue happens every time when snap is auto-refreshing a snap (possibly have to refresh multiple snap at the same time to trigger the issue) in background. If you show tasks of the current "Doing" changes, you will see it's downloading something, e.g.: `snap tasks 348`

.....
Done today at 20:50 HKT today at 20:50 HKT Ensure prerequisites for "slack" are available
Doing today at 20:50 HKT - Download snap "slack" (21) from channel "stable" (99.85%)
Do today at 20:50 HKT - Fetch and check assertions for snap "slack" (21)
.....
Done today at 20:50 HKT today at 20:53 HKT Ensure prerequisites for "<other snap>" are available
Doing today at 20:50 HKT - Download snap "<other snap>" (1038) from channel "stable" (12.17%)
.....

There will be around 5MB/s of IO when snapd is downloading something, whatever the download speed is. As the connection to Canonical's server in China is poor, people can fell this IO lasting for a long time.

I guess now the question is, why there's this 5MB/s IO when snapd is refreshing a snap?