On Wed, Mar 17, 2010 at 11:28:26AM +0900, KOSAKI Motohiro wrote: > > CONFIG_MIGRATION currently depends on CONFIG_NUMA or on the architecture > > being able to hot-remove memory. The main users of page migration such as > > sys_move_pages(), sys_migrate_pages() and cpuset process migration are > > only beneficial on NUMA so it makes sense. > > > > As memory compaction will operate within a zone and is useful on both NUMA > > and non-NUMA systems, this patch allows CONFIG_MIGRATION to be set if the > > user selects CONFIG_COMPACTION as an option. > > > > Signed-off-by: Mel Gorman <mel@xxxxxxxxx> > > Reviewed-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> > > Reviewed-by: Rik van Riel <riel@xxxxxxxxxx> > > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > > --- > > mm/Kconfig | 20 ++++++++++++++++---- > > 1 files changed, 16 insertions(+), 4 deletions(-) > > > > diff --git a/mm/Kconfig b/mm/Kconfig > > index 9c61158..04e241b 100644 > > --- a/mm/Kconfig > > +++ b/mm/Kconfig > > @@ -172,17 +172,29 @@ config SPLIT_PTLOCK_CPUS > > default "4" > > > > # > > +# support for memory compaction > > +config COMPACTION > > + bool "Allow for memory compaction" > > + def_bool y > > + select MIGRATION > > + depends on EXPERIMENTAL && HUGETLBFS && MMU > > + help > > + Allows the compaction of memory for the allocation of huge pages. > > + > > If select MIGRATION works, we can remove "depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE" > line from config MIGRATION. > I'm not quite getting why this would be an advantage. COMPACTION requires MIGRATION but conceivable both NUMA and HOTREMOVE can work without it. > > > > +# > > # support for page migration > > # > > config MIGRATION > > bool "Page migration" > > def_bool y > > - depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE > > + depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION > > help > > Allows the migration of the physical location of pages of processes > > - while the virtual addresses are not changed. This is useful for > > - example on NUMA systems to put pages nearer to the processors accessing > > - the page. > > + while the virtual addresses are not changed. This is useful in > > + two situations. The first is on NUMA systems to put pages nearer > > + to the processors accessing. The second is when allocating huge > > + pages as migration can relocate pages to satisfy a huge page > > + allocation instead of reclaiming. > > > > config PHYS_ADDR_T_64BIT > > def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT > > -- > > 1.6.5 > > > > > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>