* [Qemu-devel] Multicast network breaks under high load
@ 2015-01-27 16:22 Brian Rak
0 siblings, 0 replies; only message in thread
From: Brian Rak @ 2015-01-27 16:22 UTC (permalink / raw)
To: qemu-devel
I have two Ubuntu 14.04 KVM instances (kernel version
3.16.0-29-generic). (Running under qemu 2.2.0) They're connected using
qemu's 'multicast' network type, and basic connectivity works fine. I
can ping between the guests, they can transfer data, etc.
I'll refer to them this way:
guest1 - 10.99.0.10
guest2 - 10.99.0.11
The problem is when I send a large amount of traffic from guest2 to
guest1, guest2's network stack just stops transmitting packets. This
issue persists until I reboot guest2 (rebooting from the OS itself is
enough, I do not need to terminate and relaunch the qemu process).
Running tcpdump from within guest2, it sees incoming ARP packets:
16:09:29.197379 ARP, Request who-has 10.99.0.11 tell 10.99.0.10, length 28
16:09:30.196671 ARP, Request who-has 10.99.0.11 tell 10.99.0.10, length 28
but, it doesn't respond to them (even though the network config is fine):
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP group default qlen 1000
inet 10.99.0.11/8 brd 10.255.255.255 scope global eth1
valid_lft forever preferred_lft forever
Once this breaks, if I try to ping guest1 from guest2 I see no bytes
transmitted (via ifconfig & tcpdump). If I let ping run for a minute or
two, I start seeing:
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
Things that I've tried, that haven't prevented the issue:
* Kernel upgrade of guest2 to 3.17.1-031701-generic
* Disabling GRO on guest2
Once this breaks, none of the following will fix it:
* ifconfig eth1 down; ifconfig eth1 up
It looks to me like the virtio driver is just giving up on transmitting
packets for some reason. I'm not really sure how I would begin
troubleshooting this. Any suggestions?
For reference, guest2's network definition looks like this:
-netdev socket,mcast=230.0.0.0:6000,id=hostnet1
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2015-01-27 16:22 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-01-27 16:22 [Qemu-devel] Multicast network breaks under high load Brian Rak
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.