What triggers "No Buffer Space Available"?

[Adrian Chadd]

On 01/05/07, Marc G. Fournier <scrappy at freebsd.org> wrote:
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> I'm still being hit by this one ... more frequently right now as I had to move
> a bit more stuff *onto* that server ... I'm trying to figure out what I can
> monitor for a 'leak' somewhere, but the only thing I'm able to find is the
> whole nmbclusters stuff:
>
> mars# netstat -m | grep "mbuf clusters"
> 130/542/672/25600 mbuf clusters in use (current/cache/total/max)
>
> the above is after 26hrs uptime ...
>
> Is there something else that will trigger/generate the above error message?

It doesn't panic whe it happens, no?

I'd check the number of sockets you've currently got open at that
point. Some applications might be holding open a whole load of sockets
and their buffers stay allocated until they're closed. If they don't
handle/don't get told about the error then they'll just hold open the
mbufs.

(I came across this when banging TCP connections through a simple TCP
socket proxy and wondered why networking would lock up. Turns out
FreeBSD-6 isn't logging the "please consider raising NMBCLUSTERS"
kernel message anymore and I needed to do exactly that. Killing the
proxy process actually restored network connectivity.)


Adrian

-- 
Adrian Chadd - adrian at freebsd.org