: tldr: Recently, I tried moving an existing solrcloud configuration from : a local datacenter to EC2. Performance was roughly 1/10th what I’d : expected, until I applied a bunch of linux tweaks.
How many total nodes in your cluster? How many of them running ZooKeeper? Did you observe the heavy increase in system time CPU usage on all nodes, or just the ones running zookeeper? I ask because if your speculation is correct and it is an issue of clocksource, then perhaps ZK is where the majority of those system calls are happening, and perhaps that's why you didn't see any similar heavy system CPU load in ES? (Then again: at the lowest levels "lucene" really shouldn't care about anything clock related at all Any "time" realted code would live in the Solr level ... hmmm.) -Hoss http://www.lucidworks.com/
