[Babel-users] babeld slashes kernel route manipulation performance by 17000%

[Daniel Gröber]

Hi Toke,

Looks like I never responded to this :O.

On Thu, Feb 24, 2022 at 11:36:06PM +0100, Toke Høiland-Jørgensen wrote:
> Yeah, I find this a bit surprising as well. What kernel version are you
> seeing this on, and what does the CPU usage show while it's ongoing
> (just starting 'top' and sorting by CPU usage should show you which
> process(es) are using the most CPU time).

The CPU usage is pretty much what you'd expect babel and bird are the top
offenders but dnsmasq is also spinning quite heavily. During the original
tests I was monitoring CPU usage with htop to make sure I'm not measuring
idle route insertion activity FYI.

I just tried to reproduce the problem to make sure dnsmasq isn't
interfering also, but I can't seem to reproduce it now. Perhaps this was
actully a kernel bug that since got fixed by a kernel upgrade.

This is on a Debian 11 (bullseye) system, according to my dpkg.log I likely
had 5.10.0-11-amd64/5.10.92-1 at the time of the original tests whereas I
have 5.10.0-12-amd64/5.10.103-1 now. I tried with the old version too but I
can't seem to get the problem to trigger anymore now. Good I guess but
unsatisfying :/

> > I am aware of the babel support in bird, but in my setup the whole
> > point of using babel is for the RTT metric support which bird doesn't
> > seem to support yet.
> 
> Ah, right, yeah, it doesn't. But good to know there's demand for this,
> that's a motivation for implementing it :)

Definitely :)

--Daniel