lkml.org 
[lkml]   [2018]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm/hotplug: Optimize clear_hwpoisoned_pages
On Fri 02-11-18 23:00:01, Balbir Singh wrote:
> In hot remove, we try to clear poisoned pages, but
> a small optimization to check if num_poisoned_pages
> is 0 helps remove the iteration through nr_pages.
>
> Signed-off-by: Balbir Singh <bsingharora@gmail.com>

Makes sense to me. It would be great to actually have some number but
the optimization for the normal case is quite obvious.

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> mm/sparse.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 33307fc05c4d..16219c7ddb5f 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -724,6 +724,16 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
> if (!memmap)
> return;
>
> + /*
> + * A further optimization is to have per section
> + * ref counted num_poisoned_pages, but that is going
> + * to need more space per memmap, for now just do
> + * a quick global check, this should speed up this
> + * routine in the absence of bad pages.
> + */
> + if (atomic_long_read(&num_poisoned_pages) == 0)
> + return;
> +
> for (i = 0; i < nr_pages; i++) {
> if (PageHWPoison(&memmap[i])) {
> atomic_long_sub(1, &num_poisoned_pages);
> --
> 2.17.1
>

--
Michal Hocko
SUSE Labs

\
 
 \ /
  Last update: 2018-11-02 13:34    [W:0.038 / U:0.168 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site