lkml.org 
[lkml]   [2010]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 04/11] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove
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@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>
> > ---
> > 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


\
 
 \ /
  Last update: 2010-03-17 12:35    [W:0.118 / U:1.432 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site