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Date: Fri, 3 Feb 2012 22:19:54 +0800
From: Hillf Danton <dhillf@...il.com>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-media@...r.kernel.org, linux-mm@...ck.org,
linaro-mm-sig@...ts.linaro.org,
Michal Nazarewicz <mina86@...a86.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Russell King <linux@....linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Hillf Danton <dhillf@...il.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 08/15] mm: mmzone: MIGRATE_CMA migration type added
Hello Marek
On Fri, Feb 3, 2012 at 8:18 PM, Marek Szyprowski
<m.szyprowski@...sung.com> wrote:
> From: Michal Nazarewicz <mina86@...a86.com>
>
> The MIGRATE_CMA migration type has two main characteristics:
> (i) only movable pages can be allocated from MIGRATE_CMA
> pageblocks and (ii) page allocator will never change migration
> type of MIGRATE_CMA pageblocks.
>
> This guarantees (to some degree) that page in a MIGRATE_CMA page
> block can always be migrated somewhere else (unless there's no
> memory left in the system).
>
> It is designed to be used for allocating big chunks (eg. 10MiB)
> of physically contiguous memory. Once driver requests
> contiguous memory, pages from MIGRATE_CMA pageblocks may be
> migrated away to create a contiguous block.
>
> To minimise number of migrations, MIGRATE_CMA migration type
> is the last type tried when page allocator falls back to other
> migration types then requested.
>
> Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Tested-by: Rob Clark <rob.clark@...aro.org>
> Tested-by: Ohad Ben-Cohen <ohad@...ery.com>
> Tested-by: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> ---
> include/linux/gfp.h | 3 ++
> include/linux/mmzone.h | 38 +++++++++++++++++++----
> mm/Kconfig | 2 +-
> mm/compaction.c | 11 +++++--
> mm/page_alloc.c | 78 ++++++++++++++++++++++++++++++++++++++----------
> mm/vmstat.c | 3 ++
> 6 files changed, 108 insertions(+), 27 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 052a5b6..78d32a7 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -397,6 +397,9 @@ static inline bool pm_suspended_storage(void)
> extern int alloc_contig_range(unsigned long start, unsigned long end);
> extern void free_contig_range(unsigned long pfn, unsigned nr_pages);
>
> +/* CMA stuff */
> +extern void init_cma_reserved_pageblock(struct page *page);
> +
> #endif
>
> #endif /* __LINUX_GFP_H */
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 650ba2f..82f4fa5 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -35,13 +35,37 @@
> */
> #define PAGE_ALLOC_COSTLY_ORDER 3
>
> -#define MIGRATE_UNMOVABLE 0
> -#define MIGRATE_RECLAIMABLE 1
> -#define MIGRATE_MOVABLE 2
> -#define MIGRATE_PCPTYPES 3 /* the number of types on the pcp lists */
> -#define MIGRATE_RESERVE 3
> -#define MIGRATE_ISOLATE 4 /* can't allocate from here */
> -#define MIGRATE_TYPES 5
> +enum {
> + MIGRATE_UNMOVABLE,
> + MIGRATE_RECLAIMABLE,
> + MIGRATE_MOVABLE,
> + MIGRATE_PCPTYPES, /* the number of types on the pcp lists */
> + MIGRATE_RESERVE = MIGRATE_PCPTYPES,
> +#ifdef CONFIG_CMA
> + /*
> + * MIGRATE_CMA migration type is designed to mimic the way
> + * ZONE_MOVABLE works. Only movable pages can be allocated
> + * from MIGRATE_CMA pageblocks and page allocator never
> + * implicitly change migration type of MIGRATE_CMA pageblock.
> + *
> + * The way to use it is to change migratetype of a range of
> + * pageblocks to MIGRATE_CMA which can be done by
> + * __free_pageblock_cma() function. What is important though
> + * is that a range of pageblocks must be aligned to
> + * MAX_ORDER_NR_PAGES should biggest page be bigger then
> + * a single pageblock.
> + */
> + MIGRATE_CMA,
> +#endif
> + MIGRATE_ISOLATE, /* can't allocate from here */
> + MIGRATE_TYPES
> +};
> +
> +#ifdef CONFIG_CMA
> +# define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
> +#else
> +# define is_migrate_cma(migratetype) false
> +#endif
>
> #define for_each_migratetype_order(order, type) \
> for (order = 0; order < MAX_ORDER; order++) \
> diff --git a/mm/Kconfig b/mm/Kconfig
> index e338407..3922002 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -198,7 +198,7 @@ config COMPACTION
> config MIGRATION
> bool "Page migration"
> def_bool y
> - depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION
> + depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA
> help
> Allows the migration of the physical location of pages of processes
> while the virtual addresses are not changed. This is useful in
> diff --git a/mm/compaction.c b/mm/compaction.c
> index d5174c4..a6e7c64 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -45,6 +45,11 @@ static void map_pages(struct list_head *list)
> }
> }
>
> +static inline bool migrate_async_suitable(int migratetype)
Just nitpick, since the helper is not directly related to what async means,
how about migrate_suitable(int migrate_type) ?
> +{
> + return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
> +}
> +
> /*
> * Isolate free pages onto a private freelist. Caller must hold zone->lock.
> * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
> @@ -277,7 +282,7 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
> */
> pageblock_nr = low_pfn >> pageblock_order;
> if (!cc->sync && last_pageblock_nr != pageblock_nr &&
> - get_pageblock_migratetype(page) != MIGRATE_MOVABLE) {
> + migrate_async_suitable(get_pageblock_migratetype(page))) {
Here compaction looks corrupted if CMA not enabled, Mel?
btw, Kame-san is not Cced correctly 8;/
Hillf
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