Re: Kernel panic: Route cache, RCU, possibly FIB trie.

[Jesper Dangaard Brouer <hawk@diku.dk>]

On Thu, 23 Mar 2006, Eric Dumazet wrote:

> Jesper Dangaard Brouer a écrit :
>
> > > grep . /proc/sys/net/ipv4/route/*
> > > /proc/sys/net/ipv4/route/error_burst:5000
> > > /proc/sys/net/ipv4/route/error_cost:1000
> > > grep: /proc/sys/net/ipv4/route/flush: Operation not permitted
> > > /proc/sys/net/ipv4/route/gc_elasticity:8
> > > /proc/sys/net/ipv4/route/gc_interval:60
> > > /proc/sys/net/ipv4/route/gc_min_interval:0
> > > /proc/sys/net/ipv4/route/gc_min_interval_ms:500
> > > /proc/sys/net/ipv4/route/gc_thresh:65536
> > > /proc/sys/net/ipv4/route/gc_timeout:300
> > > /proc/sys/net/ipv4/route/max_delay:10
> > > /proc/sys/net/ipv4/route/max_size:1048576
> > > /proc/sys/net/ipv4/route/min_adv_mss:256
> > > /proc/sys/net/ipv4/route/min_delay:2
> > > /proc/sys/net/ipv4/route/min_pmtu:552
> > > /proc/sys/net/ipv4/route/mtu_expires:600
> > > /proc/sys/net/ipv4/route/redirect_load:20
> > > /proc/sys/net/ipv4/route/redirect_number:9
> > > /proc/sys/net/ipv4/route/redirect_silence:20480
> > > /proc/sys/net/ipv4/route/secret_interval:600
>
> I would say : Change the settings :)
>
> echo 2 > /proc/sys/net/ipv4/route/gc_elasticity
> echo 1 > /proc/sys/net/ipv4/route/gc_interval
> echo 131072 > /proc/sys/net/ipv4/route/gc_thresh

These parameters do not solve the problem. I think you missed my previous 
point.  The parameter that needs adjustment is:

 /proc/sys/net/ipv4/route/max_size

The garbage collector will not be activated before the number of 
entries are above "max_size" (see: function rt_garbage_collect).

I have set:
 /proc/sys/net/ipv4/route/gc_thresh:30000
 /proc/sys/net/ipv4/route/max_size:30000

Which solves the problem of the route cache growing too large too fast.


I have read the route.c code again, to see if I missed something. Are you 
trying to make the function "rt_check_expire" to do the cleanup?

I have tried your parameters, and it does not have the desired effect.


> and watch the output of :
>
> rtstat -c 100 -i 1
> (you might have to recompile lnstat/rtstat from iproute2 package from
> http://developer.osdl.org/dev/iproute2/download/

I prefer to use Robert's version of rtstat ;-)

Hilsen
  Jesper Brouer

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