Marconi Rivello
2007-Aug-08 11:25 UTC
[Xen-users] Live migration downtime longer when mem < maxmem
Hi there, I am experiencing a weird (at least to me) behavior in live migration. I have 2 VMs, one with 1024M maxmem and another with 512M maxmem. When i set the VM mem to max-mem, I get around 3s of downtime. When I reduce the mem to half the max-mem, I get around 20s downtime! I tested with both VMs. Just a note: both VMs and phys. machines are idle, the network isn''t dedicated, but the tests were run consecutively and repeated times. I''m also working on figuring out why the downtime is longer than a few ms, as described in Xen papers. I think it has to do with the switch... But in the meantime, why on earth should a VM''s migration take longer when I reduce it''s mem? I appreciate any ideas, theories, or even a trivial explanation that would make me look silly :) Thanks. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Marconi Rivello
2007-Aug-08 12:13 UTC
[Xen-users] Live migration downtime longer when mem < maxmem
Hi there, I am experiencing a weird (at least to me) behavior in live migration. I have 2 VMs, one with 1024M maxmem and another with 512M maxmem. When i set the VM mem to max-mem, I get around 3s of downtime. When I reduce the mem to half the max-mem, I get around 20s downtime! I tested with both VMs. Just a note: both VMs and phys. machines are idle, the network isn''t dedicated, but the tests were run consecutively and repeated times. I''m also working on figuring out why the downtime is longer than a few ms, as described in Xen papers. I think it has to do with the switch... But in the meantime, why on earth should a VM''s migration take longer when I reduce it''s mem? I appreciate any ideas, theories, or even a trivial explanation that would make me look silly :) Thanks. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Tim Wood
2007-Aug-17 22:41 UTC
Re: [Xen-users] Live migration downtime longer when mem < maxmem
It may or may not have ever been resolved, but there were some messages about this a while back... you may have some luck searching the archives to see if tehre was a conclusive fix: http://lists.xensource.com/archives/html/xen-devel/2006-12/msg00903.html http://lists.xensource.com/archives/html/xen-users/2006-09/msg00131.html -Tim On 8/8/07, Marconi Rivello <marconirivello@gmail.com> wrote:> Hi there, > > I am experiencing a weird (at least to me) behavior in live migration. > > I have 2 VMs, one with 1024M maxmem and another with 512M maxmem. When i set > the VM mem to max-mem, I get around 3s of downtime. When I reduce the mem to > half the max-mem, I get around 20s downtime! I tested with both VMs. > > Just a note: both VMs and phys. machines are idle, the network isn''t > dedicated, but the tests were run consecutively and repeated times. I''m also > working on figuring out why the downtime is longer than a few ms, as > described in Xen papers. I think it has to do with the switch... > > But in the meantime, why on earth should a VM''s migration take longer when I > reduce it''s mem? > > I appreciate any ideas, theories, or even a trivial explanation that would > make me look silly :) > > Thanks. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users