Is this still an issue for you? There were some actual KSM corruption bugs which were somewhat recently fixed.
KSM in general wil use more CPU in order to reduce memory contention, so your results are not necessarily unexpected. Aside from turning KSM off, you can also reduce the KSM frequency. There are some other tuning hints at http://www.linux- kvm.org/page/Tuning_Kernel ** Changed in: qemu-kvm (Ubuntu) Status: New => Incomplete ** Changed in: qemu-kvm (Ubuntu) Importance: Undecided => Low -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1368439 Title: Random high latency with KSM enabled and multiple CPU sockets Status in linux package in Ubuntu: Incomplete Status in qemu-kvm package in Ubuntu: Incomplete Bug description: If running a box with multiple CPU sockets and Ubuntu 14.04 Server 64-bit qemu-kvm with KSM enabled as by default, random high latency occurs on network connections for VMs, as high as 4000ms - 5000ms. The host also reports high IO wait times. Disabling KSM fixed this for me. I run the same setup on boxes with only 1 CPU socket and it's not an issue. qemu-kvm version: Installed: 2.0.0+dfsg-2ubuntu1.3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1368439/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
