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: ===BEGIN stress-highalloc STRESS-HIGHALLOC stress-highalloc highalloc-3.6.0 3.6.0-rc5 rc5-patch Pass 1 47.00 ( 0.00%) 85.00 (38.00%) Pass 2 52.00 ( 0.00%) 87.00 (35.00%) while Rested 77.00 ( 0.00%) 99.00 (22.00%) MMTests Statistics: duration 3.6.0 3.6.0 rc5 rc5-patch User 1566.87 1066.77 System 948.78 713.19 Elapsed 2008.95 1650.72 MMTests Statistics: vmstat 3.6.0 3.6.0 rc5 rc5-patch Page Ins 5037962 3458106 Page Outs 10779728 8969512 Swap Ins 34282 5565 Swap Outs 63027 19717 Direct pages scanned 481017 166920 Kswapd pages scanned 2083130 1537202 Kswapd pages reclaimed 1838615 1459932 Direct pages reclaimed 337487 120613 Kswapd efficiency 88% 94% Kswapd velocity 1036.925 931.231 Direct efficiency 70% 72% Direct velocity 239.437 101.120 Percentage direct scans 18% 9% Page writes by reclaim 157305 19855 Page writes file 94278 138 Page writes anon 63027 19717 Page reclaim immediate 111205 64510 Page rescued immediate 0 0 Slabs scanned 3362816 2375680 Direct inode steals 12411 2022 Kswapd inode steals 753789 524457 Kswapd skipped wait 136 7 THP fault alloc 688 739 THP collapse alloc 378 481 THP splits 279 317 THP fault fallback 172 45 THP collapse fail 12 5 Compaction stalls 1378 968 Compaction success 406 595 Compaction failures 972 373 Compaction pages moved 3104073 1790932 Compaction move failure 92713 41252 ===END stress-highalloc Rafael Aquini (5): mm: introduce a common interface for balloon pages mobility mm: introduce compaction and migration for ballooned pages virtio_balloon: introduce migration primitives to balloon pages mm: introduce putback_movable_pages() mm: add vm event counters for balloon pages compaction drivers/virtio/virtio_balloon.c | 306 ++++++++++++++++++++++++++++++++++--- include/linux/balloon_compaction.h | 147 ++++++++++++++++++ include/linux/migrate.h | 2 + include/linux/pagemap.h | 18 +++ include/linux/vm_event_item.h | 8 +- mm/Kconfig | 15 ++ mm/Makefile | 1 + mm/balloon_compaction.c | 154 +++++++++++++++++++ mm/compaction.c | 51 ++++--- mm/migrate.c | 57 ++++++- mm/page_alloc.c | 2 +- mm/vmstat.c | 10 +- 12 files changed, 726 insertions(+), 45 deletions(-) create mode 100644 include/linux/balloon_compaction.h create mode 100644 mm/balloon_compaction.c Change log: v10: * Adjust leak_balloon() wait_event logic to make a clear locking scheme (MST); * Drop the RCU protection approach for dereferencing balloon's page->mapping; * Minor nitpitcks on code commentaries (MST); v9: * Adjust rcu_dereference usage to leverage page lock protection (Paul, Peter); * Enhance doc on compaction interface introduced to balloon driver (Michael); * Fix issue with isolated pages breaking leak_balloon() logics (Michael); v8: * introduce a common MM interface for balloon driver page compaction (Michael); * remove the global state preventing multiple balloon device support (Michael); * introduce RCU protection/syncrhonization to balloon page->mapping (Michael); v7: * fix a potential page leak case at 'putback_balloon_page' (Mel); * adjust vm-events-counter patch and remove its drop-on-merge message (Rik); * add 'putback_movable_pages' to avoid hacks on 'putback_lru_pages' (Minchan); v6: * rename 'is_balloon_page()' to 'movable_balloon_page()' (Rik); v5: * address Andrew Morton's review comments on the patch series; * address a couple extra nitpick suggestions on PATCH 01 (Minchan); 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; -- 1.7.11.4 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
