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SubjectRe: [PATCH 05/12] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove
On Fri, Feb 19, 2010 at 09:21:11AM +0900, KAMEZAWA Hiroyuki wrote:
> On Thu, 18 Feb 2010 18:02:35 +0000
> Mel Gorman <mel@csn.ul.ie> 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@csn.ul.ie>
> > Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
> > Reviewed-by: Rik van Riel <riel@redhat.com>
>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> But see below.
>
> > ---
> > mm/Kconfig | 20 ++++++++++++++++----
> > 1 files changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index 17b8947..b1c2781 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -168,17 +168,29 @@ 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
> > + help
> > + Allows the compaction of memory for the allocation of huge pages.
> > +
>
> I think
> + depends on MMU
>

Agreed. Thanks

> > +#
> > # 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
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@kvack.org. For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> >
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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