I just spent 3 weeks trying to solve a performance problem that showed up when I upgraded to Ubuntu 15.10 (from 14.04). Here are the details in case anybody else runs into it.
Every time I tried to display a large image (using ImageMagick's "display" command, geeqie, Google Chrome, etc.), if I was also running VMware Workstation 12 at the time, the entire system's performance plummeted. The vmware-vmx process would hog the CPU (100-200%, according to "top"). My VM guests would slow to a crawl, the host's window manager would become unresponsive, and so on. Strangely, the CPU load reported by the VM guest OSes was nearly zero... they weren't doing anything. But the second I shut down my VM guests, the problem vanished. A process called "khugepaged" was also visible sometimes as the problem occurred. (Ominous music plays....) VMware tech support spent 2 weeks debugging with me over email, trying all sorts of options. It's a beefy computer (12 cores, 32 GB RAM), so this slowdown was really weird. The problem remained no matter what we tried. Then I ran across this article tonight: http://unversioned.blogspot.com/2015/10/vmware-workstation-11-ubuntu-high-cpu-utilization.html Sure enough, when I made the recommended khugepaged-related change, disabling "transparent hugepages" in the host as suggested, the symptoms vanished. # echo never > /sys/kernel/mm/transparent_hugepage/enabled # echo never > /sys/kernel/mm/transparent_hugepage/defrag I don't understand much about khugepaged except that it's supposed to be (ironically) a performance optimization: http://www.phoronix.com/scan.php?page=article&item=linux_transparent_hugepages Can anybody explain what might have been happening here, and whether I am losing anything important by disabling transparent hugepages? Thank you, Dan -- Dan Barrett [email protected] _______________________________________________ Discuss mailing list [email protected] http://lists.blu.org/mailman/listinfo/discuss
