Rpi3 smsc0: warning: failed to create new mbuf

[Ronald Klop]

Check sysctl kern.ipc.nmbclusters and netstat -m | grep "mbuf clusters".
The default is pretty low on rpi3.

I run this script every hour from cron which is a 'poor man's' autotune.  
Works for me though.

[root at rpi3 ~]# cat bin/nmbclustercheck.sh
#! /bin/sh

LINE=$( netstat -m | grep "mbuf clusters" | cut -d ' ' -f 1 )
CURRENT=$( echo $LINE | cut -d '/' -f 1 )
MAX=$( echo $LINE | cut -d '/' -f 4 )

if test $CURRENT -gt $(( $MAX / 2 ))
then
	NEW_MAX=$(( $MAX * 2 ))
	echo Increase kern.upc.nmbclusters from $MAX to $NEW_MAX
	sysctl kern.ipc.nmbclusters=$NEW_MAX
fi

Regards,
Ronald.


On Mon, 25 Nov 2019 21:05:13 +0100, bob prohaska <fbsd at www.zefox.net>  
wrote:

> An RPI3 running 13.0-CURRENT #0 r355024 stalled with a flood of
> smsc0: warning: failed to create new mbuf
> on the console. It was compiling www/chromium.
>
> The debugger started without difficulty, but unfortunately
> I neglected to capture a backtrace. The machine rebooted
> without difficulty and has resumed the build of www/chromium.
>
> Is a backtrace worth collecting if it happens again?
>
> Thanks for reading,
>
> bob prohaska
>
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