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

[Daniel Gröber]

Hi,

I'm seeing a rather odd issue in my babeld deployment. I'm using babeld on
one of my linux routers which also has bird running with a v6 BGP full
table session thats being inserted into the kernel FIB.

Whenever bird tries to clear/reinsert all routes in the kernel table I'm
seeing a 17000% reduction[1] in route insertion performance if babled is
running simultaniously :)

Since I've anticipated babeld not being quite ready to even see/filter a
kernel table with 100k+ routes I've set things up such that bird inserts
its routes into a separate table so babeld has a chance to just completely
ignore them and only see a nice and short main routing table.

Any ideas/pointers how babled could be slowing this down so much?

--Daniel

[1]: Measured by counting how many lines ip monitor spits out over a 10
second period while bird is having at it with or without babeld running,
thusly: `timeout 10 ip -6 monitor | wc -l`.

With babeld:

    root at Debby:~# { timeout 10 ip -6 monitor; } | wc -l
    296

Without babled:

    root at Debby:~# { timeout 10 ip -6 monitor; } | wc -l
    104809
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