Hi We experienced packet drops and high CPU on one core (only) on a multicore VR on high volume traffic.
After extensive investigation, we identified the irq balancing is not
working properly, as a result only one core was used for IRQ handing of
TCP for all 3 interfaces:
# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3
72: 2704675402 0 0 0 PCI-MSI-edge eth0-rxtx-0
73: 1272554833 0 0 0 PCI-MSI-edge eth0-rxtx-1
74: 1277628455 0 0 0 PCI-MSI-edge eth0-rxtx-2
75: 1278457419 0 0 0 PCI-MSI-edge eth0-rxtx-3
76: 0 0 0 0 PCI-MSI-edge eth0-event-4
77: 450819 0 0 0 PCI-MSI-edge eth1-rxtx-0
78: 370442 0 0 0 PCI-MSI-edge eth1-rxtx-1
79: 317069 0 0 0 PCI-MSI-edge eth1-rxtx-2
80: 401197 0 0 0 PCI-MSI-edge eth1-rxtx-3
81: 0 0 0 0 PCI-MSI-edge eth1-event-4
82: 2768559207 0 0 0 PCI-MSI-edge eth2-rxtx-0
83: 1328122336 0 0 0 PCI-MSI-edge eth2-rxtx-1
84: 1328017908 0 0 0 PCI-MSI-edge eth2-rxtx-2
85: 1322146180 0 0 0 PCI-MSI-edge
Restarting /etc/init.d/ircbalance did not help, but you will find some
log entries in /var/log/daemon.log
irqbalance: WARNING: MSI interrupts found in /proc/interrupts
irqbalance: But none found in sysfs, you need to update your kernel
irqbalance: Until then, IRQs will be improperly classified
It turns out, this is a known issue on Debian Wheezy irqbalance version
1.0.3-3 https://lists.debian.org/debian-user/2013/05/msg00512.html and
was patched in 1.0.4-1.
But the good know is, there is 1.0.6 in wheezy-backports
aptitude update
aptitude install -t wheezy-backports irqbalance
That helped.
Can this be included in the SystemVM templates as well?
Yours
René
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