Re: Unable to handle a connection wall

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, May 28, 2009 at 02:02:36PM -0400, Arnaud Lacombe wrote:
> Hi,
> 
> I have a soekris box, currently running 5.0RC3 which is unable to
> handle a 100-connections wall (almost simultaneous). This is quite
> frustrating knowing that the box is idle and just rebooted. The error
> on the console is the following:
> 
> vr1: unable to allocate Tx cluster
> [....]
> vr1: unable to allocate Tx cluster
> vr1: unable to allocate Tx cluster
> vr1: unable to allocate Tx cluster
> 
> followed by:
> 
> WARNING: mclpool limit reached; increase NMBCLUSTERS.
> 
> A few minutes after this, the mbuf usage is still really high:
> 
> # netstat -m
> 11130 mbufs in use:
>         10773 mbufs allocated to data
>         357 mbufs allocated to packet headers
> 8265 calls to protocol drain routines

You could have a look at netstat -an, see if there's lot of data in the
queues.

> 
> The drain calls count increment, but nothing is freed.
> 
> The initial message from vr1 is due to a failed MGETHDR().
> 
> Btw, is there any way to change NMBCLUSTERS on an i386 system without
> have either to reboot or build a new kernel ?

No, the kern.mbuf.nmbclusters sysctl isn't writable on i386.
You can change the nmbclusters global with gdb --write /netbsd though,
this avoids a rebuild.

> 
> Thanks,
> 
>  - Arnaud
> 
> ps: at the end of the redaction of this mail, the mbuf usage finally dropped:
> 
> # netstat -m
> 2234 mbufs in use:
>         1978 mbufs allocated to data
>         256 mbufs allocated to packet headers
> 8278 calls to protocol drain routines
> 
> ... but the box still not accessible through the network (even ARP
> stays unanswered).

Maybe a ifconfig down/up on the network interface would help ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--