Tuesday, December 18, 2012

Passthrough PCIe devices from ESXi to FreeBSD - Leave MSI Enabled to Avoid Interrupt Storms With More than One vCPU

If you want to pass a PCIe device (such as a LSI SAS controller) through ESXi to a FreeBSD VM, you're probably aware that you may need to disable MSI/MSI-X interrupts to make it work.

However, I'm finding that while this setting will make the system boot, if you add a second vCPU, you will quickly stat to see Interrupt Storm messages on your console, and one of your CPU's will be nearly 100% used on interrupt tasks.

The easy fix for me? Only disable MSIX, not MSI.

Here are the relevant lines from my /boot/loader.conf:


All of my interrupt storm issues are now gone. 

Wednesday, December 12, 2012

VMWare Enhanced vMotion Compatibility (EVC) Not Needed between AMD Bulldozer 6234 and AMD Piledriver 6348 on VMware ESXi 5.1

I recently upgraded one of our datacenter servers from an AMD Bulldozer 6234 to a AMD Piledriver 6348.

I did find the new chip was faster for memory/CPU operations in our VM's, but I'll post about that in a different article.

What surprised me was that I didn't need to turn on EVC to allow VM's to migrate between hosts running the different CPU's.

Either VMware 5.1 doesn't recognize the new instruction set, or they don't matter in terms of migration.

Either way, I can migrate to the newer chips without worry, and since the 63xx are socket compatible with the 62xx and 61xx series, I have a fairly easy upgrade path for our servers if I wish.