Re: ipvsadm: One-packet scheduling with UDP service is unstable

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Sat, 24 Aug 2013 22:15:16 +0800
Drunkard Zhang <gongfan193@gmail.com> wrote:

> >         May be we can enable debug for short time when
> > OPS is not working:
> >
> > # Start debug for 10ms
> > echo 20 > /proc/sys/net/ipv4/vs/debug_level
> > usleep 10000
> > # Stop debug
> > echo 0 > /proc/sys/net/ipv4/vs/debug_level

Just some general notes on debugging.

Debug verbose levels:
 -  1 is least verbose
 - 12 is most verbose
 -  0 disables debugging

Kernel needs to be compiled with CONFIG_IP_VS_DEBUG=y

To get even more detailed debugging. The macro IP_VS_DBG_PKT uses
debug_pr() to print its messages.  If the kernel is configured with
dynamic debug (CONFIG_DYNAMIC_DEBUG), you will not see these messages.
To enable these messages, do the following:

 mount -t debugfs none /sys/kernel/debug/
 cat /sys/kernel/debug/dynamic_debug/control | grep ipvs

 echo "func ip_vs_tcpudp_debug_packet_v6 +p" > /sys/kernel/debug/dynamic_debug/control
 echo "func ip_vs_tcpudp_debug_packet_v4 +p" > /sys/kernel/debug/dynamic_debug/control

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer