Re: [RFC PATCH 1/5] mm/vmstat: retrieve suitable free pageblock information just once

[Vlastimil Babka <vbabka@suse.cz>]

On 01/13/2017 08:14 AM, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> It's inefficient to retrieve buddy information for fragmentation index
> calculation on every order. By using some stack memory, we could retrieve
> it once and reuse it to compute all the required values. MAX_ORDER is
> usually small enough so there is no big risk about stack overflow.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Sounds useful regardless of the rest of the series.

Acked-by: Vlastimil Babka <vbabka@suse.cz>

A nit below.

> ---
>  mm/vmstat.c | 25 ++++++++++++-------------
>  1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 7c28df3..e1ca5eb 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -821,7 +821,7 @@ unsigned long node_page_state(struct pglist_data *pgdat,
>  struct contig_page_info {
>  	unsigned long free_pages;
>  	unsigned long free_blocks_total;
> -	unsigned long free_blocks_suitable;
> +	unsigned long free_blocks_order[MAX_ORDER];

No need to rename _suitable to _order IMHO. The meaning is still the
same, it's just an array now. For me a name "free_blocks_order" would
suggest it's just simple zone->free_area[order].nr_free.

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