On Sat, Aug 25, 2012 at 02:24:55AM -0300, Rafael Aquini 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
Meta-question: are there any numbers showing gain from this patchset?
The reason I ask, on migration we notify host about each page
individually. If this is rare maybe the patchset does not help much.
If this is common we would be better off building up a list of multiple
pages and passing them in one go.
> 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 | 287
> ++++++++++++++++++++++++++++++++++---
> include/linux/balloon_compaction.h | 137 ++++++++++++++++++
> include/linux/migrate.h | 2 +
> include/linux/pagemap.h | 18 +++
> include/linux/vm_event_item.h | 8 +-
> mm/Kconfig | 15 ++
> mm/Makefile | 2 +-
> mm/balloon_compaction.c | 174 ++++++++++++++++++++++
> mm/compaction.c | 51 ++++---
> mm/migrate.c | 57 +++++++-
> mm/page_alloc.c | 2 +-
> mm/vmstat.c | 10 +-
> 12 files changed, 715 insertions(+), 48 deletions(-)
> create mode 100644 include/linux/balloon_compaction.h
> create mode 100644 mm/balloon_compaction.c
>
>
> Change log:
> 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;
>
>
> Preliminary test results:
> (2 VCPU 2048mB RAM KVM guest running 3.6.0_rc3+ -- 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_isolated 0
> compact_balloon_migrated 0
> compact_balloon_released 0
> compact_balloon_returned 0
> [root@localhost ~]#
> [root@localhost ~]# for i in $(seq 1 6); 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
> [5]- Done echo 1 > /proc/sys/vm/compact_memory
> [6]+ Done echo 1 > /proc/sys/vm/compact_memory
> [root@localhost ~]#
> [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat
> compact_blocks_moved 3108
> compact_pages_moved 43169
> compact_pagemigrate_failed 95
> compact_stall 0
> compact_fail 0
> compact_success 0
> compact_balloon_isolated 16384
> compact_balloon_migrated 16384
> compact_balloon_released 16384
> compact_balloon_returned 0
>
>
> * 128 mB 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_isolated 0
> compact_balloon_migrated 0
> compact_balloon_released 0
> compact_balloon_returned 0
> [root@localhost ~]#
> [root@localhost ~]# for i in $(seq 1 6); 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
> [5]- Done echo 1 > /proc/sys/vm/compact_memory
> [6]+ Done echo 1 > /proc/sys/vm/compact_memory
> [root@localhost ~]#
> [root@localhost ~]# awk '/compact/ {print}' /proc/vmstat
> compact_blocks_moved 3062
> compact_pages_moved 49774
> compact_pagemigrate_failed 129
> compact_stall 0
> compact_fail 0
> compact_success 0
> compact_balloon_isolated 26076
> compact_balloon_migrated 25957
> compact_balloon_released 25957
> compact_balloon_returned 119
>
> --
> 1.7.11.4
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