On Fri, 15 Mar 2013 00:36:35 +0900 (JST)
HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
> If buddy page has order n, (2^n) pages are filtered at the same
> time. Then, next (2^n) pages are already filterd, so we can skip the
> (2^n) pages for free.
>
> By this, on 32GB memory system, there's the following improvement:
>
> - with mmap() on /proc/vmcore from 0.594421 seconds to 0.496517
> seconds, and
> - with normal read() from 1.533796 seconds to 0.750935 seconds.
>
> Note that the two improvements are measured on the same /proc/vmcore.
>
> Note also that amount of the improvement depends on amount of free
> pages, though it's obvious.
>
> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
Good ! Applied.
Thanks
Atsushi Kumagai
> ---
> makedumpfile.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 7acbf72..9075f38 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -4303,9 +4303,9 @@ __exclude_unnecessary_pages(unsigned long mem_map,
> && info->flag_cyclic
> && info->page_is_buddy
> && info->page_is_buddy(flags, _mapcount, private, _count)) {
> - int i;
> + int i, nr_pages = 1 << private;
>
> - for (i = 0; i < (1 << private); ++i) {
> + for (i = 0; i < nr_pages; ++i) {
> /*
> * According to combination of
> * MAX_ORDER and size of cyclic
> @@ -4318,6 +4318,9 @@ __exclude_unnecessary_pages(unsigned long mem_map,
> clear_bit_on_2nd_bitmap_for_kernel(pfn + i);
> }
> pfn_free += i;
> +
> + pfn += nr_pages - 1;
> + mem_map += (nr_pages - 1) * SIZE(page);
> }
> /*
> * Exclude the cache page without the private page.
> --
> 1.8.1.4
>
>
>
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