On Fri, Mar 04, 2016 at 10:11:00AM +0000, Li, Liang Z wrote: > > On Fri, Mar 04, 2016 at 09:12:12AM +0000, Li, Liang Z wrote: > > > > Although I wonder which is cheaper; that would be fairly expensive > > > > for the guest wouldn't it? And you'd somehow have to kick the guest > > > > before migration to do the ballooning - and how long would you wait for > > it to finish? > > > > > > About 5 seconds for an 8G guest, balloon to 1G. Get the free pages > > > bitmap take about 20ms for an 8G idle guest. > > > > > > Liang > > > > Where is the time spent though? allocating within guest? > > Or passing the info to host? > > If the former, we can use existing inflate/deflate vqs: > > Have guest put each free page on inflate vq, then on deflate vq. > > > > Maybe I am not clear enough. > > I mean if we inflate balloon before live migration, for a 8GB guest, it takes about 5 Seconds for the inflating operation to finish. And these 5 seconds are spent where? > For the PV solution, there is no need to inflate balloon before live migration, the only cost is to traversing the free_list to > construct the free pages bitmap, and it takes about 20ms for a 8GB idle guest( less if there is less free pages), > passing the free pages info to host will take about extra 3ms. > > > Liang So now let's please stop talking about solutions at a high level and discuss the interface changes you make in detail. What makes it faster? Better host/guest interface? No need to go through buddy allocator within guest? Less interrupts? Something else? > > -- > > MST -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>