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 patchset follows the main idea discussed at 2012 LSFMMS section: "Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/ to introduce the required changes to the virtio_balloon driver, as well as 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. Rafael Aquini (4): mm: introduce compaction and migration for virtio ballooned pages virtio_balloon: handle concurrent accesses to virtio_balloon struct elements virtio_balloon: introduce migration primitives to balloon pages mm: add vm event counters for balloon pages compaction drivers/virtio/virtio_balloon.c | 142 +++++++++++++++++++++++++++++++++++---- include/linux/mm.h | 15 +++++ include/linux/virtio_balloon.h | 4 ++ include/linux/vm_event_item.h | 2 + mm/compaction.c | 127 ++++++++++++++++++++++++++++------ mm/migrate.c | 32 ++++++++- mm/vmstat.c | 4 ++ 7 files changed, 293 insertions(+), 33 deletions(-) Changelog: V3: address reviwers nitpick suggestions (Mel, Minchan) V2: address Mel Gorman's review comments Preliminary test results: (2 VCPU 1024mB RAM KVM guest running 3.5.0_rc5+) * 64mB balloon: [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat compact_blocks_moved 0 compact_pages_moved 0 compact_pagemigrate_failed 0 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 0 compact_balloon_failed 0 compact_balloon_isolated 0 compact_balloon_freed 0 [root@localhost ~]# [root@localhost ~]# for i in $(seq 1 4); do echo 1 > /proc/sys/vm/compact_memory & done &>/dev/null [1] Done echo 1 > /proc/sys/vm/compact_memory [2] Done echo 1 > /proc/sys/vm/compact_memory [3]- Done echo 1 > /proc/sys/vm/compact_memory [4]+ Done echo 1 > /proc/sys/vm/compact_memory [root@localhost ~]# [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat compact_blocks_moved 2717 compact_pages_moved 46697 compact_pagemigrate_failed 75 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 16384 compact_balloon_failed 0 compact_balloon_isolated 16384 compact_balloon_freed 16384 * 128mB balloon: [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat compact_blocks_moved 0 compact_pages_moved 0 compact_pagemigrate_failed 0 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 0 compact_balloon_failed 0 compact_balloon_isolated 0 compact_balloon_freed 0 [root@localhost ~]# [root@localhost ~]# for i in $(seq 1 4); do echo 1 > /proc/sys/vm/compact_memory & done &>/dev/null [1] Done echo 1 > /proc/sys/vm/compact_memory [2] Done echo 1 > /proc/sys/vm/compact_memory [3]- Done echo 1 > /proc/sys/vm/compact_memory [4]+ Done echo 1 > /proc/sys/vm/compact_memory [root@localhost ~]# [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat compact_blocks_moved 2598 compact_pages_moved 47660 compact_pagemigrate_failed 103 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 26652 compact_balloon_failed 76 compact_balloon_isolated 26728 compact_balloon_freed 26652 -- 1.7.10.2 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
