CPU Utilization is Wrong
I use `htop` for all of my Linux machines. It's great software. But one of my biggest gripes is that "Detailed CPU Time" (F2 -> Display options -> Detailed CPU time) is not enabled by default.<p>Enabling it allows you to see a clearer picture of not just stalls but also CPU steal from "noisy neighbors" -- guests also assigned to the same host.<p>I've seen CPU steal cause kernel warnings of "soft-lockups". I've also seen zombie processes occur. I suspect they're related but it's only anecdotal: I'm not sure how to investigate.<p>It's pretty amazing what kind of patterns you can identify when you've got stuff like that running. Machine seems to be non-responsive? Open up htop, see lots of grey... okay so since <i>all</i> data is on the network, that means that it's a data bottleneck; over the network means it could be bottlenecked at network bandwidth or the back-end SAN could be bottlenecked.<p>Fun fact: Windows Server doesn't like not having its disk IO not be serviced for minutes at a time. That's not a fun way to have another team come over and get angry because you're bluescreening their production boxes.