Re: [PATCH 04/14] Allow CONFIG_MIGRATION to be set withoutCONFIG_NUMA or memory hot-remove
From: Andrew Morton
Date: Tue Apr 06 2010 - 20:06:47 EST
On Fri, 2 Apr 2010 17:02:38 +0100
Mel Gorman <mel@xxxxxxxxx> 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.
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -172,6 +172,16 @@ 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.
Seems strange to depend on hugetlbfs. Perhaps depending on
HUGETLB_PAGE would be more logical.
But hang on. I wanna use compaction to make my order-4 wireless skb
allocations work better! Why do you hate me?
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