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 512mB RAM in 64mB chunks, at every minute (inflating/deflating), while test was running: ===BEGIN stress-highalloc STRESS-HIGHALLOC highalloc-3.7 highalloc-3.7 rc4-clean rc4-patch Pass 1 55.00 ( 0.00%) 62.00 ( 7.00%) Pass 2 54.00 ( 0.00%) 62.00 ( 8.00%) while Rested 75.00 ( 0.00%) 80.00 ( 5.00%) MMTests Statistics: duration 3.7 3.7 rc4-clean rc4-patch User 1207.59 1207.46 System 1300.55 1299.61 Elapsed 2273.72 2157.06 MMTests Statistics: vmstat 3.7 3.7 rc4-clean rc4-patch Page Ins 3581516 2374368 Page Outs 11148692 10410332 Swap Ins 80 47 Swap Outs 3641 476 Direct pages scanned 37978 33826 Kswapd pages scanned 1828245 1342869 Kswapd pages reclaimed 1710236 1304099 Direct pages reclaimed 32207 31005 Kswapd efficiency 93% 97% Kswapd velocity 804.077 622.546 Direct efficiency 84% 91% Direct velocity 16.703 15.682 Percentage direct scans 2% 2% Page writes by reclaim 79252 9704 Page writes file 75611 9228 Page writes anon 3641 476 Page reclaim immediate 16764 11014 Page rescued immediate 0 0 Slabs scanned 2171904 2152448 Direct inode steals 385 2261 Kswapd inode steals 659137 609670 Kswapd skipped wait 1 69 THP fault alloc 546 631 THP collapse alloc 361 339 THP splits 259 263 THP fault fallback 98 50 THP collapse fail 20 17 Compaction stalls 747 499 Compaction success 244 145 Compaction failures 503 354 Compaction pages moved 370888 474837 Compaction move failure 77378 65259 ===END stress-highalloc Rafael Aquini (7): mm: adjust address_space_operations.migratepage() return code mm: redefine address_space.assoc_mapping 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 | 139 +++++++++++++++-- fs/buffer.c | 12 +- fs/gfs2/glock.c | 2 +- fs/hugetlbfs/inode.c | 4 +- fs/inode.c | 2 +- fs/nilfs2/page.c | 2 +- include/linux/balloon_compaction.h | 263 ++++++++++++++++++++++++++++++++ include/linux/fs.h | 2 +- include/linux/migrate.h | 19 +++ include/linux/pagemap.h | 16 ++ include/linux/vm_event_item.h | 7 +- mm/Kconfig | 15 ++ mm/Makefile | 3 +- mm/balloon_compaction.c | 304 +++++++++++++++++++++++++++++++++++++ mm/compaction.c | 27 +++- mm/migrate.c | 86 ++++++++--- mm/page_alloc.c | 2 +- mm/vmstat.c | 9 +- 18 files changed, 862 insertions(+), 52 deletions(-) create mode 100644 include/linux/balloon_compaction.h create mode 100644 mm/balloon_compaction.c Change log: v12: * Address last suggestions on sorting the barriers usage out (Mel Gorman); * Fix reported build breakages for CONFIG_BALLOON_COMPACTION=n (Andrew Morton); * Enhance commentary on the locking scheme used for balloon page compaction; * Move all the 'balloon vm_event counter' changes to PATCH 07; v11: * Address AKPM's last review suggestions; * Extend the balloon compaction common API and simplify its usage at driver; * Minor nitpicks on code commentary; 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; -- 1.7.11.7 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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