[Xen-API] Flood test with xen/openvswitch

[Sébastien Riccio <sr@xxxxxxxxxxxxxxx>]

Hi,

I just did a test to see how openvswitch handle a flood from a virtual 
machine on a xen
host using it as the networking layer.

I just issued a :

vm1# hping3  -S -L 0 -p 80 -i u100 192.168.1.1

options I used are:
-S set SYN tcp flag
-L set ACK tcp flag
-p destination port
-i u100 = interval between packets in micro seconds

This results in a cpu usage up to 97% by the ovs-vswitchd process in the 
dom0.
Letting it go for a few minutes turns the whole xen host unresponsive to 
network access
and must then be accessed from the local console.

Is that an excepted behavior ? I know the test is quite agressive but 
any customer could issue such a flood
and render the whole host unreachable. Are there workarounds ?

Thanks for your help.

Best regards,
Sébastien

part of the openvswitch logs when issuing the flood:

Sep 07 13:13:26|01523|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:26|01524|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:27|01525|poll_loop|WARN|Dropped 5136 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:27|01526|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:27|01527|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:28|01528|poll_loop|WARN|Dropped 5815 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:28|01529|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:28|01530|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (85% 
CPU usage)
Sep 07 13:13:29|01531|poll_loop|WARN|Dropped 8214 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:29|01532|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:29|01533|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:30|01534|poll_loop|WARN|Dropped 5068 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:30|01535|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:30|01536|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:31|01537|poll_loop|WARN|Dropped 5008 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:31|01538|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:31|01539|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (82% 
CPU usage)
Sep 07 13:13:32|01540|poll_loop|WARN|Dropped 4841 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:32|01541|poll_loop|WARN|wakeup due to 40-ms timeout at 
../ofproto/ofproto-dpif.c:622 (83% CPU usage)
Sep 07 13:13:32|01542|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (83% 
CPU usage)
Sep 07 13:13:33|01543|poll_loop|WARN|Dropped 92 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:33|01544|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (83% 
CPU usage)
Sep 07 13:13:33|01545|poll_loop|WARN|wakeup due to [POLLIN] on fd 21 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (83% 
CPU usage)
Sep 07 13:13:34|01546|poll_loop|WARN|Dropped 27 log messages in last 1 
seconds (most recently, 1 seconds ago) due to excessive rate
Sep 07 13:13:34|01547|poll_loop|WARN|wakeup due to 53-ms timeout at 
../lib/mac-learning.c:294 (83% CPU usage)
Sep 07 13:13:34|01548|poll_loop|WARN|wakeup due to [POLLIN] on fd 18 
(NETLINK_GENERIC<->NETLINK_GENERIC) at ../lib/netlink-socket.c:668 (83% 
CPU usage)

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