Messages in this thread Patch in this message | | | Date | Mon, 29 Jun 2015 16:32:55 +0900 | From | Kamezawa Hiroyuki <> | Subject | Re: [RFC v2 PATCH 2/8] mm: introduce MIGRATE_MIRROR to manage the mirrored pages |
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On 2015/06/27 11:24, Xishi Qiu wrote: > This patch introduces a new migratetype called "MIGRATE_MIRROR", it is used to > allocate mirrored pages. > When cat /proc/pagetypeinfo, you can see the count of free mirrored blocks. > > Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
My fear about this approarch is that this may break something existing.
Now, when we add MIGRATE_MIRROR type, we'll hide attributes of pageblocks as MIGRATE_UNMOVABOLE, MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE.
Logically, MIRROR attribute is independent from page mobility and this overwrites will make some information lost.
Then,
> --- > include/linux/mmzone.h | 9 +++++++++ > mm/page_alloc.c | 3 +++ > mm/vmstat.c | 3 +++ > 3 files changed, 15 insertions(+) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 54d74f6..54e891a 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -39,6 +39,9 @@ enum { > MIGRATE_UNMOVABLE, > MIGRATE_RECLAIMABLE, > MIGRATE_MOVABLE, > +#ifdef CONFIG_MEMORY_MIRROR > + MIGRATE_MIRROR, > +#endif
I think MIGRATE_MIRROR_UNMOVABLE, MIGRATE_MIRROR_RECLAIMABLE, MIGRATE_MIRROR_MOVABLE, <== adding this may need discuss. MIGRATE_MIRROR_RESERVED, <== reserved pages should be maintained per mirrored/unmirrored.
should be added with the following fallback list.
/* * MIRROR page range is defined by firmware at boot. The range is limited * and is used only for kernel memory mirroring. */ [MIGRATE_UNMOVABLE_MIRROR] = {MIGRATE_RECLAIMABLE_MIRROR, MIGRATE_RESERVE} [MIGRATE_RECLAIMABLE_MIRROR] = {MIGRATE_UNMOVABLE_MIRROR, MIGRATE_RESERVE}
Then, we'll not lose the original information of "Reclaiable Pages".
One problem here is whteher we should have MIGRATE_RESERVE_MIRROR.
If we never allow users to allocate mirrored memory, we should have MIGRATE_RESERVE_MIRROR. But it seems to require much more code change to do that.
Creating a zone or adding an attribues to zones are another design choice.
Anyway, your patch doesn't takes care of reserved memory calculation at this point. Please check setup_zone_migrate_reserve() That will be a problem.
Thanks, -Kame
> MIGRATE_PCPTYPES, /* the number of types on the pcp lists */ > MIGRATE_RESERVE = MIGRATE_PCPTYPES, > #ifdef CONFIG_CMA > @@ -69,6 +72,12 @@ enum { > # define is_migrate_cma(migratetype) false > #endif > > +#ifdef CONFIG_MEMORY_MIRROR > +# define is_migrate_mirror(migratetype) unlikely((migratetype) == MIGRATE_MIRROR) > +#else > +# define is_migrate_mirror(migratetype) false > +#endif > + > #define for_each_migratetype_order(order, type) \ > for (order = 0; order < MAX_ORDER; order++) \ > for (type = 0; type < MIGRATE_TYPES; type++) > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index ebffa0e..6e4d79f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3216,6 +3216,9 @@ static void show_migration_types(unsigned char type) > [MIGRATE_UNMOVABLE] = 'U', > [MIGRATE_RECLAIMABLE] = 'E', > [MIGRATE_MOVABLE] = 'M', > +#ifdef CONFIG_MEMORY_MIRROR > + [MIGRATE_MIRROR] = 'O', > +#endif > [MIGRATE_RESERVE] = 'R', > #ifdef CONFIG_CMA > [MIGRATE_CMA] = 'C', > diff --git a/mm/vmstat.c b/mm/vmstat.c > index 4f5cd97..d0323e0 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -901,6 +901,9 @@ static char * const migratetype_names[MIGRATE_TYPES] = { > "Unmovable", > "Reclaimable", > "Movable", > +#ifdef CONFIG_MEMORY_MIRROR > + "Mirror", > +#endif > "Reserve", > #ifdef CONFIG_CMA > "CMA", >
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