On Mon, 17 Sep 2012 13:38:15 -0300 Rafael Aquini <aquini@xxxxxxxxxx> wrote: > Memory fragmentation introduced by ballooning might reduce significantly > the number of 2MB contiguous memory blocks that can be used within a guest, > thus imposing performance penalties associated with the reduced number of > transparent huge pages that could be used by the guest workload. > > This patch-set follows the main idea discussed at 2012 LSFMMS session: > "Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/ > to introduce the required changes to the virtio_balloon driver, as well as > the changes to the core compaction & migration bits, in order to make those > subsystems aware of ballooned pages and allow memory balloon pages become > movable within a guest, thus avoiding the aforementioned fragmentation issue > > Following are numbers that prove this patch benefits on allowing compaction > to be more effective at memory ballooned guests. > > Results for STRESS-HIGHALLOC benchmark, from Mel Gorman's mmtests suite, > running on a 4gB RAM KVM guest which was ballooning 1gB RAM in 256mB chunks, > at every minute (inflating/deflating), while test was running: How can a patchset reach v10 and have zero Reviewed-by's? The patchset looks reasonable to me and your empirical results look good. But I don't feel that I'm in a position to decide on its overall desirability, either in a standalone sense or in comparison to any alternative schemes which anyone has proposed. IOW, Rusty and KVM folks: please consider thyself poked. I looked through the code and have some comments which are minor in the overall scheme of things. I'll be more comfortable when a compaction expert has had a go over it. IOW, Mel joins the pokee list ;) (The question of "overall desirability" is the big one here. Do we actually want to add this to Linux? The rest is details which we can work out). -- 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>