On September 28, 2011, Daniel P. Berrange wrote: > On Tue, Sep 27, 2011 at 04:04:41PM -0600, Thomas Fjellstrom wrote: > > On September 27, 2011, Avi Kivity wrote: > > > On 09/27/2011 03:29 AM, Thomas Fjellstrom wrote: > > > > I just noticed something interesting, a virtual machine on one of my > > > > servers seems to have 69 threads (including the main thread). Other > > > > guests on the machine only have a couple threads. > > > > > > > > Is this normal? or has something gone horribly wrong? > > > > > > It's normal if the guest does a lot of I/O. The thread count should go > > > down when the guest idles. > > > > Ah, that would make sense. Though it kind of defeats assigning a vm a > > single cpu/core. A single VM can now DOS an entire multi-core-cpu > > server. It pretty much pegged my dual core (with HT) server for a couple > > hours. > > You can mitigate these problems by putting each KVM process in its own > cgroup, and using the 'cpu_shares' tunable to ensure that each KVM > process gets the same relative ratio of CPU time, regardless of how > many threads it is running. With newer kernels there are other CPU > tunables for placing hard caps on CPU utilization of the process as > a whole too. I'll have to look into how to set that up with libvirt. A brief search leads me to believe its rather easy to set up, so I'll have to do that asap :) > Regards, > Daniel -- Thomas Fjellstrom thomas@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
