> > > Suggestion to address all above comments: > > > 1. allocate a bunch of pages and link them up, > > > calculating the min and the max pfn. > > > if max-min exceeds the allocated bitmap size, > > > tell host. > > > > I am not sure if it works well in some cases, e.g. The allocated pages > > are across a wide range and the max-min > limit is very frequently to be > true. > > Then, there will be many times of virtio transmission and it's bad for > > performance improvement. Right? > > It's a tradeoff for sure. Measure it, see what the overhead is. > Hi MST, I have measured the performance when using a 32K page bitmap, and inflate the balloon to 3GB of an idle guest with 4GB RAM. Now: total inflating time: 338ms the count of virtio data transmission: 373 the call count of madvise: 865 before: total inflating time: 175ms the count of virtio data transmission: 1 the call count of madvise: 42 Maybe the result will be worse if the guest is not idle, or the guest has more RAM. Do you want more data? Is it worth to do that? Liang > > > > > 2. limit allocated bitmap size to something reasonable. > > > How about 32Kbytes? This is 256kilo bit in the map, which comes > > > out to 1Giga bytes of memory in the balloon. > > > > So, even the VM has 1TB of RAM, the page bitmap will take 32MB of > memory. > > Maybe it's better to use a big page bitmap the save the pages > > allocated by balloon, and split the big page bitmap to 32K bytes unit, then > transfer one unit at a time. > > How is this different from what I said? > > > > > Should we use a page bitmap to replace 'vb->pages' ? > > > > How about rolling back to use PFNs if the count of requested pages is a > small number? > > > > Liang > > That's why we have start pfn. you can use that to pass even a single page > without a lot of overhead. > > > > > -- > > > > 1.9.1 > > > -- > > > To unsubscribe from this list: send the line "unsubscribe kvm" in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > > > info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
