On 2015/8/4 22:27, Dave Hansen wrote:
> On 08/03/2015 06:13 PM, Xishi Qiu wrote:
>> How did you do the experiment?
>
> I just stuck in some counters in expand() that looked to see whether the
> list was empty or not when the page is added and then printed them out
> occasionally.
>
Hi Dave,
I add some debug code like this, but it doesn't trigger the dump_stack().
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -834,6 +834,12 @@ static inline void expand(struct zone *zone, struct page
*page,
continue;
}
#endif
+
+ if (!list_empty(&area->free_list[migratetype])) {
+ printk("expand(), the list is not empty\n");
+ dump_stack();
+ }
+
list_add(&page[size].lru, &area->free_list[migratetype]);
area->nr_free++;
set_page_order(&page[size], high);
> It will be interesting to see the results both on a freshly-booted
> system and one that's reached relatively steady-state and is moving
> around a minimal number of pageblocks between the different types.
>
> In any case, the end result here needs to be some indication that the
> patch either helps ease fragmentation or helps performance.
>
> .
>
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