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

To: Drunkard Zhang <gongfan193@xxxxxxxxx>
Subject: Re: ipvsadm: One-packet scheduling with UDP service is unstable
Cc: Julian Anastasov <ja@xxxxxx>, lvs-devel@xxxxxxxxxxxxxxx, brouer@xxxxxxxxxx
From: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Date: Wed, 28 Aug 2013 12:47:32 +0200
On Sat, 24 Aug 2013 22:15:16 +0800
Drunkard Zhang <gongfan193@xxxxxxxxx> 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" > 
 echo "func ip_vs_tcpudp_debug_packet_v4 +p" > 

Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of
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