What's the meaning of "dst cache overflow"

[Lore]

Hi,

my gateway is running a 2.6.2 vanilla kernel. Since some time it is putting the message "dst cache overflow" in /var/log/messages. What's the meaning of that? Google has'nt given me an answer yet.

[David_Escott]

Where is this error coming from? What program? A message in /var/log/messages will look like:

progname[pid] date and time message

[Lore]

[David_Escott]

Its in linux/net/ipv4/route.c. The dst is the protocol independent destination cache (routing cache). A garbage collection routine is run to clear out old old destination entries if the cache is getting too big, and this warning is thrown if that garbage collection is unsuccessful (either interrupted or jiffies) and net_ratelimit() is true, although I can't find where that function is defined.

If you want to fiddle with things you might look at the kernel's routing cache but I suspect this warning arises when there are sudden spikes in traffic volume to different destinations.

PS route.c has lots of interesting comments about martians in it rather funny.

[Lore]

net_ratelimit() is defined in include/linux/net.h and implemented in /net/core/utils.c:

/*
42 * This enforces a rate limit: not more than one kernel message
43 * every 5secs to make a denial-of-service attack impossible.
44 *
45 * All warning printk()s should be guarded by this function.
46 */


http://t08server/extern/statistik/mrtg/ping/172.20.254.254.icmp.html

Here you can see what happend, suddenly packet loss gets to 100%, the gateway doesn't answer any more and the error messages occurs.

[Instinct82]

any ideas howto prevent this error?
_________________
my gentoo boxes
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Intel Pentium 90, 128MB RAM, True Headless

[j-m]