Performance Issue due To IRQ Sharing


You’ve noticed some performance degradation of your ESX host but you cannot poke at anything… Maybe IRQ sharing is the culprit!
SSH in your ESX host and type in cat /proc/interrupts

           CPU0
  0:  401683019       vmnix-edge  timer
  1:          3                     vmnix-edge  keyboard
  2:  250124011       vmnix-edge  VMnix interrupt
 16:  516382092      vmnix-level  usb-uhci, ehci_hcd
 17:          0                  vmnix-level  usb-uhci
 18:  108396478     vmnix-level  usb-uhci
 19:  208200983     vmnix-level  usb-uhci
 20:  183643037     vmnix-level  ipmi_si
 21:   14679561       vmnix-level  usb-uhci, cpqci
NMI:          0
LOC:          0
ERR:          0
MIS:          0

You can see here the huge amount of IRQ request for the USB modules.  It’s time to unload that module. At the console, type in rmmod usb-uhci
And finally to prevent the COS to load the driver, remove or comment out from the file /etc/modules.conf

By theb way ESXi version 3 and 4 don’t suffer from this issue because they do not have any COS. Time to upgrade 🙂

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About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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