Re: [PATCH v16 7/9] mm: Rotate free list so reported pages are moved to the tail of the list

David Hildenbrand
2020-01-08T13:39:23Z

On 03.01.20 22:16, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>
> Rather than walking over the same pages again and again to get to the pages
> that have yet to be reported we can save ourselves a significant amount of
> time by simply rotating the list so that when we have a full list of
> reported pages the head of the list is pointing to the next non-reported
> page. Doing this should save us some significant time when processing each
> free list.
>
> This doesn't gain us much in the standard case as all of the non-reported
> pages should be near the top of the list already. However in the case of
> page shuffling this results in a noticeable improvement. Below are the
> will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without
> this patch.
>
> Without:
> tasks processes processes_idle threads threads_idle
> 16 8093776.25 0.17 5393242.00 38.20
>
> With:
> tasks processes processes_idle threads threads_idle
> 16 8283274.75 0.17 5594261.00 38.15
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> mm/page_reporting.c | 30 ++++++++++++++++++++++--------
> 1 file changed, 22 insertions(+), 8 deletions(-)

Just a minor comment while scanning over the patches (will do more
review soon), you might want to switch to "mm/page_reporting: " styled
subjects for these optimizations.

--
Thanks,

David / dhildenb