Re: [libvirt-users] dramatic performance slowdown due to THP allocation failure with full pagecache

On 14 November 2017 at 10:56, Daniel P. Berrange wrote: > Oh well THP usage inside the guest is then not really anything todo with > virt, just a regular Linux questions, so not sure libvirt is the best > place to ask. True, I just hoped you or one of the other devs might have some insight on rec

Re: [libvirt-users] dramatic performance slowdown due to THP allocation failure with full pagecache

Thanks for the reply Daniel, However I think you slightly misunderstood the scenario... On 14 November 2017 at 10:32, Daniel P. Berrange wrote: > IOW, if your application has a certain expectation of performance that can > only > be satisfied by having the KVM guest backed by huge pages, then y

[libvirt-users] dramatic performance slowdown due to THP allocation failure with full pagecache

Hi all, This is not really a libvirt issue but I'm hoping some of the smart folks here will know more about this problem... We have noticed when running some HPC applications on our OpenStack (libvirt+KVM) cloud that the same application occasionally performs much worse (4-5x slowdown) than norma

Re: [libvirt-users] high memory guest issues - virsh start and QEMU_JOB_WAIT_TIME

On 15 February 2017 at 20:40, Daniel P. Berrange wrote: > On Wed, Feb 15, 2017 at 10:27:46AM +0100, Michal Privoznik wrote: >> On 02/15/2017 03:43 AM, Blair Bethwaite wrote: >> > On 15 February 2017 at 00:57, Daniel P. Berrange >> > wrote: >> >> What is

Re: [libvirt-users] high memory guest issues - virsh start and QEMU_JOB_WAIT_TIME

On 15 February 2017 at 00:57, Daniel P. Berrange wrote: > What is the actual error you're getting during startup. # virsh -d0 start instance-037c start: domain(optdata): instance-037c start: found option : instance-037c start: trying as domain NAME error: Failed to start domain insta

[libvirt-users] high memory guest issues - virsh start and QEMU_JOB_WAIT_TIME

Hi all, In IRC last night Dan helpfully confirmed my analysis of an issue we are seeing attempting to launch high memory KVM guests backed by hugepages... In this case the guests have 240GB of memory allocated from two host NUMA nodes to two guest NUMA nodes. The trouble is that allocating the hu

Re: [libvirt-users] How to best I/O performance for Window2008 and MSSQL guest VM

Hi Roberto, On 6 December 2016 at 19:01, Roberto Fichera wrote: > I've set to copy host configuration (16 cores) and memory is set to 24GB, > host has 64GB. > Guest is Windows 2012 64bits version Is the guest configured with 16 cpus or 16 cores? >> Are you pinning to dedicated CPUs, > >no I w

Re: [libvirt-users] How to best I/O performance for Window2008 and MSSQL guest VM

Hi Roberto, What is the cpu and memory configuration of your guest? Are you pinning to dedicated CPUs, are you exposing host topology and cpu features, do you have dedicated I/O threads? Are you backing the guest memory with hugepages? All of the above will likely increase performance and minimise