Re: [PATCH v2 3/5] mm/page_alloc: Optimize free_area_init_core

On Thu, Jul 19, 2018 at 03:44:17PM +0200, Michal Hocko wrote:

On Thu 19-07-18 15:27:38, osalvador@techadventures.net wrote:

quoted

From: Oscar Salvador <osalvador@suse.de>

In free_area_init_core we calculate the amount of managed pages
we are left with, by substracting the memmap pages and the pages
reserved for dma.
With the values left, we also account the total of kernel pages and
the total of pages.

Since memmap pages are calculated from zone->spanned_pages,
let us only do these calculcations whenever zone->spanned_pages is greather
than 0.

But why do we care? How do we test this? In other words, why is this
worth merging?

 
Uhm, unless the values are going to be updated, why do we want to go through all
comparasions/checks?
I thought it was a nice thing to have the chance to skip that block unless we are going to
update the counters.

Again, if you think this only adds complexity and no good, I can drop it.

Thanks
-- 
Oscar Salvador
SUSE L3