Re: [Xen-API] Flood test with xen/openvswitch

[George Shuklin <george.shuklin@xxxxxxxxx>]

I think this can be real issue.

We have a bunch of highloaded hosts with multiple CPUs in dom0 (used to
reduce network latency in load peaks).

So I'm thinking issue can be not with openvswitch, but with
hardware/compability with xen...

Ð ÐÑ., 07/09/2011 Ð 10:43 -0400, Andres E. Moya ÐÐÑÐÑ:
> wouldn't this give us the crashing issue that has been occurring in xen?
> 
> recntly i had to run this command
> echo "NR_DOMAIN0_VCPUS=1" > /etc/sysconfig/unplug-vcpus to stop xen from 
> crashing, its been running for 24 hours now.
> 
> Moya Solutions, Inc.
> amoya@xxxxxxxxxxxxxxxxx
> 0 | 646-918-5238 x 102
> F | 646-390-1806
> 
> ----- Original Message -----
> From: "George Shuklin" <george.shuklin@xxxxxxxxx>
> To: xen-api@xxxxxxxxxxxxxxxxxxx
> Sent: Wednesday, September 7, 2011 9:59:13 AM
> Subject: Re: [Xen-API] Flood test with xen/openvswitch
> 
> temporary solution: add more active cpus to dom0.
> echo 1 >/sys/devices/system/cpu/cpu1/online
> echo 1 >/sys/devices/system/cpu/cpu2/online
> echo 1 >/sys/devices/system/cpu/cpu3/online
> 
> Ð ÐÑ., 07/09/2011 Ð 13:29 +0200, SÃbastien Riccio ÐÐÑÐÑ:
> > 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,
> > SÃbastien
> > 
> > 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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> > xen-api@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/mailman/listinfo/xen-api
> 
> 
> 
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