On Tue, Nov 26, 2013 at 12:31:12 -0800, Chegu Vinod wrote:
On 11/26/2013 4:24 AM, Jiri Denemark wrote:
On Thu, Nov 21, 2013 at 17:47:24 -0800, Chegu Vinod wrote:
Busy enterprise workloads hosted on large sized VM's tend to dirty memory faster than the transfer rate achieved via live guest migration. Despite some good recent improvements (& using dedicated 10Gig NICs between hosts) the live migration may NOT converge.
Recently support was added in qemu (version 1.6) to allow a user to choose if they wish to force convergence of their migration via a new migration capability : "auto-converge". This feature allows for qemu to auto-detect lack of convergence and trigger a throttle-down of the VCPUs.
This RFC patch includes the libvirt support needed to trigger this feature. (Testing is still in progress) ... So except for the small issues, the patch looks good to me. However, do I remember correctly that this feature can be turned on dynamically for an already running migration? If so, I think we want a second patch adding a new API for setting this auto-converge feature.
Yes.
Is there a sample reference/example that I could look up ?
You can have a look at virConnectGetCPUModelNames, which is the most recent simple API added to libvirt (commits f90857b32aa81f9a5e878e7bceb2df30e2b1b4f8, fd69544965ddf0e49e40c99d24708da4ba1a7648, cbcecd7ab14de22467c405023580afcb9e8eca54, ea45b23cfc2b75053aea96f29a2a91cfc8e26013) but n qemu_driver.c you will need to use QEMU_JOB_MIGRATION_OP as the job type (the third parameter to qemuDomainObjBeginJob) to make this API working during migration. Jirka