From 18468d93e53b037e1a04ec58398eab763d054064 Mon Sep 17 00:00:00 2001 From: Rafael Aquini Date: Tue, 11 Dec 2012 16:02:38 -0800 Subject: mm: introduce a common interface for balloon pages mobility 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 introduces a common interface to help a balloon driver on making its page set movable to compaction, and thus allowing the system to better leverage the compation efforts on memory defragmentation. [akpm@linux-foundation.org: use PAGE_FLAGS_CHECK_AT_PREP, s/__balloon_page_flags/page_flags_cleared/, small cleanups] [rientjes@google.com: allow balloon compaction for any system with memory compaction enabled, which is the defconfig] Signed-off-by: Rafael Aquini Acked-by: Mel Gorman Cc: Rusty Russell Cc: "Michael S. Tsirkin" Cc: Rik van Riel Cc: Andi Kleen Cc: Konrad Rzeszutek Wilk Cc: Minchan Kim Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Kconfig | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'mm/Kconfig') diff --git a/mm/Kconfig b/mm/Kconfig index a3f8dddaaab3..e6651c5de14f 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -187,6 +187,21 @@ config SPLIT_PTLOCK_CPUS default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC default "4" +# +# support for memory balloon compaction +config BALLOON_COMPACTION + bool "Allow for balloon memory compaction/migration" + def_bool y + depends on COMPACTION && VIRTIO_BALLOON + help + 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. Allowing the compaction & migration for memory + pages enlisted as being part of memory balloon devices avoids the + scenario aforementioned and helps improving memory defragmentation. + # # support for memory compaction config COMPACTION -- cgit v1.2.3-70-g09d2