bobrik

Expensive memory.stat + cpu.stat

We're seeing issues where cadvisor spends a lot of time on CPU.

Repro

The following should run on any system with systemd (code is in this gist):

go run main.go

bobrik

Calls into skb:kfree_skb

As requested in netdev, this gist contains the stacks leading into skb:kfree_skb:

• https://lore.kernel.org/netdev/[email protected]/

The easiest way to look at the results is the flamegraphs, where reason is the top frame.

The results are from v6.1.38.

bobrik

unix_gc overload

The issue

Linux kernel has a garbage collection mechanism for inflight unix sockets passed to other unix sockets. This mechanism can be used to cause excessive load onto well behaved processes that are using regular unix sockets without any fd passing, because garbage collection is called in the socket write path.

The repro

bobrik

Amcrest cleanup script

Handy if you want to keep the most recent Amcrest recordings around.

Example output:

$ ./cleanup.py -s $((400 * 1024)) /Volumes/cameras
Checked /Volumes/cameras/amcrest02/2023-11-11/001/dav
Checked /Volumes/cameras/amcrest02/2023-11-07/001/dav