dsa: mv88e6xxx rstp convergence test

Dear all,

i am testing three switches connected together, the switches are
linux-based using mv88e6xxx dsa driver on kernel 5.4.70. rstp is active 
as a daemon at userspace level.


    SW A  ---- Host
    /    \
SW B --- SW C


A host connected to A sends 1000 arp requests per secs
to SW B, while i disconnect the root path, to test convergence.

Convergence happens sometimes < 50 msec, sometimes near 100.

Do you think i can get a constant convergence time < 50 msec
in some other way ?

Thanks a lot,
angelo