Re: [PATCH] mm/page_alloc: call set_pageblock_order() once for each node

[Michal Hocko <mhocko@suse.com>]

On Fri 30-03-18 09:02:43, Wei Yang wrote:
> On Thu, Mar 29, 2018 at 01:11:09PM +0100, Mel Gorman wrote:
> >On Thu, Mar 29, 2018 at 11:36:07AM +0800, Wei Yang wrote:
> >> set_pageblock_order() is a standalone function which sets pageblock_order,
> >> while current implementation calls this function on each ZONE of each node
> >> in free_area_init_core().
> >> 
> >> Since free_area_init_node() is the only user of free_area_init_core(),
> >> this patch moves set_pageblock_order() up one level to invoke
> >> set_pageblock_order() only once on each node.
> >> 
> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> >
> >The patch looks ok but given that set_pageblock_order returns immediately
> >if it has already been called, I expect the benefit is marginal. Was any
> >improvement in boot time measured?
> 
> No, I don't expect measurable improvement from this since the number of nodes
> and zones are limited.
> 
> This is just a code refine from logic point of view.

Then, please make sure it is a real refinement. Calling this function
per node is only half way to get there as the function is by no means
per node.

-- 
Michal Hocko
SUSE Labs