Greetings all,
I'm experiencing Tx queue hangs with the ixgbe driver.
The scenario that I am running is the following:
1. Have two X540-AT2 nics, and connect them through a cable
2. For each of the two nics create a virtual function from the host OS
Ex: echo 1 > /sys/class/net/enp5s0f1/device/sriov_numvfs
3. Create two guest virtual machines, and assign the PFs to them (not the
virtual functions)
4. Boot up the guests, and try to send some packets through the
interfaces that will be managed by the ixgbe driver
Ex: ping 1.1.1.1 -I eth1
5. Notice that the adapter keeps resetting due to a Tx queue hanging
The dmesg log shows the following information:
ixgbe 0000:00:08.0: eth1: Detected Tx Unit Hang
Tx Queue <0>
TDH, TDT <2>, <3>
next_to_use <3>
next_to_clean <0>
tx_buffer_info[next_to_clean]
time_stamp <1000d00d6>
jiffies <1000d0a95>
ixgbe 0000:00:08.0: eth1: tx hang 4 detected on queue 0, resetting adapter
ixgbe 0000:00:08.0: eth1: Reset adapter
ixgbe 0000:00:08.0: eth1: NIC Link is Up 10 Gbps, Flow Control: RX/TX
Also, running ethtool tests on the NIC shows that it's in an
inconsistent state
[root@localhost ~]# ethtool -t eth1
The test result is FAIL
The test extra info:
Register test (offline) 0
Eeprom test (offline) 0
Interrupt test (offline) 0
Loopback test (offline) 13
Link test (on/offline) 0
I would add that if I were to remove the VF interfaces prior to assigning the
PF to the guests, the problem does not happen anymore,
which makes me suspect it's a configuration related to the way that the
transmit queues are configured in the case of VFs being enabled.
My setup is the following:
1. NIC: Intel Corporation Ethernet Controller 10-Gigabit X540-AT2
2. Hypervisor:
Type: KVM
Distro: CentOS 7
Kernel: 3.10.0-229.4.2.el7.x86_64
3. Guest
Distro: CentOS 6.3
Kernel: Customized 3.10 kernel , but saw the problem with a default CentOS
stock kernel as well (2.6.32-279.el6.x86_64)
Ixgbe version: 3.6.7-k
For now, as a workaround I can disable the virtual functions, before using
pass-through on the PF.
I would like to understand better why does this problem happen, and if there
are any patches that attempt to fix the issue.
I know there are a few problems related to when SR-IOV and DCB are
simultaneously enabled [1] , but I don't think this is the case in my setup.
My customized guest kernel has CONFIG_DCB and CONFIG_PCI_IOV disabled while the
stock kernel from CentOS has them enabled, yet I manage to see the problem in
both cases.
[1] http://www.spinics.net/lists/netdev/msg203427.html
Thanks,
Tudor
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