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SubjectRe: [mm PATCH v3 3/6] mm: Use memblock/zone specific iterator for handling deferred page init
On Mon 15-10-18 13:27:09, Alexander Duyck wrote:
> This patch introduces a new iterator for_each_free_mem_pfn_range_in_zone.
>
> This iterator will take care of making sure a given memory range provided
> is in fact contained within a zone. It takes are of all the bounds checking
> we were doing in deferred_grow_zone, and deferred_init_memmap. In addition
> it should help to speed up the search a bit by iterating until the end of a
> range is greater than the start of the zone pfn range, and will exit
> completely if the start is beyond the end of the zone.
>
> This patch adds yet another iterator called
> for_each_free_mem_range_in_zone_from and then uses it to support
> initializing and freeing pages in groups no larger than MAX_ORDER_NR_PAGES.
> By doing this we can greatly improve the cache locality of the pages while
> we do several loops over them in the init and freeing process.
>
> We are able to tighten the loops as a result since we only really need the
> checks for first_init_pfn in our first iteration and after that we can
> assume that all future values will be greater than this. So I have added a
> function called deferred_init_mem_pfn_range_in_zone that primes the
> iterators and if it fails we can just exit.

Numbers please.

Besides that, this adds a lot of code and I am not convinced the result
is so much better to justify that.

> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> include/linux/memblock.h | 58 +++++++++++++++
> mm/memblock.c | 63 ++++++++++++++++
> mm/page_alloc.c | 176 ++++++++++++++++++++++++++++++++--------------
> 3 files changed, 242 insertions(+), 55 deletions(-)
--
Michal Hocko
SUSE Labs

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