On 11/02/2012 05:10 AM, David Gibson wrote: > Asking for some advice on the list. > > I have prorotype savevm and migration support ready for the pseries > machine. They seem to work under simple circumstances (idle guest). > To test them more extensively I've been attempting to perform live > migrations (just over tcp->localhost) which the guest is active with > something. In particular I've tried while using octave to do matrix > multiply (so exercising the FP unit) and my colleague Alexey has tried > during some video encoding. > As you are doing local migration one option is to setting the speed higher than line speed , as we don't actually send the data, another is to set high downtime.
> However, in each of these cases, we've found that the migration only > completes and the source instance only stops after the intensive > workload has (just) completed. What I surmise is happening is that > the workload is touching memory pages fast enough that the ram > migration code is never getting below the threshold to complete the > migration until the guest is idle again. > The workload you chose is really bad for live migration, as all the guest does is dirtying his memory. I recommend looking for workload that does some networking or disk IO. Vinod succeeded running SwingBench and SLOB benchmarks that converged ok, I don't know if they run on pseries, but similar workload should be ok(small database/warehouse). We found out that SpecJbb on the other hand is hard to converge. Web workload or video streaming also do the trick. Cheers, Orit > Does anyone have some ideas for testing this better: workloads that > are less likely to trigger this behaviour, or settings to tweak in the > migration itself to make it more likely to complete migration while > the workload is still active. >
