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-- 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/1346917 Title: Using KSM on NUMA capable machines can cause KVM guest performance and stability issues Status in “linux” package in Ubuntu: Fix Released Status in “linux” source package in Trusty: Fix Released Bug description: [Impact] When using KVM on NUMA machines, both Linux and Windows guests can exhibit very poor performance and potential crashes. Disabling KSM is a known workaround to fix this issue. [Fix] The following patch fixes the issue in our testing: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=64a9a34e22896dad430e21a28ad8cb00a756fefc This patch is present in v3.14-rc1 and onwards. [Test Case] General test case: 1) On a NUMA capable machine, setup the machine as a KVM hypervisor - lscpu should show more than 1 NUMA node 2) Install 4 KVM VMs 3) Run the following in another terminal to ensure that pages_shared and pages_sharing is increasing - watch 'tail /sys/kernel/mm/ksm/*' 4) In another terminal run a program that continually pings each node and alerts on high latencies What we've observed is that in Linux guests, the ping latencies can go into the ~2 second range for a few pings, then return back to the < 1ms range. (This is machine dependent.) In addition, occasionally when running this test with Windows guests we observe BSODs during this test. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1346917/+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
