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 Rafael Aquini (3): mm: introduce compaction and migration for virtio ballooned pages virtio_balloon: introduce migration primitives to balloon pages mm: add vm event counters for balloon pages compaction drivers/virtio/virtio_balloon.c | 146 ++++++++++++++++++++++++++++++++++++--- 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, 302 insertions(+), 28 deletions(-) Change log: v4: * address Rusty Russel's review comments on PATCH 02; * re-base virtio_balloon patch on 9c378abc5c0c6fc8e3acf5968924d274503819b3; V3: * address reviewers nitpick suggestions on PATCH 01 (Mel, Minchan); V2: * address Mel Gorman's review comments on PATCH 01; Preliminary test results: (2 VCPU 1024mB RAM KVM guest running 3.5.0_rc7+ -- after a reboot) * 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 2842 compact_pages_moved 48429 compact_pagemigrate_failed 81 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 16364 compact_balloon_failed 0 compact_balloon_isolated 16364 compact_balloon_freed 16364 * 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 2162 compact_pages_moved 33735 compact_pagemigrate_failed 69 compact_stall 0 compact_fail 0 compact_success 0 compact_balloon_migrated 21731 compact_balloon_failed 0 compact_balloon_isolated 21731 compact_balloon_freed 21731 -- 1.7.10.4 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
