Messages in this thread | | | Date | Thu, 15 Aug 2013 14:38:56 +0800 | From | Xishi Qiu <> | Subject | Re: [PATCH] mm: skip the page buddy block instead of one page |
| |
On 2013/8/15 12:17, Minchan Kim wrote:
> > Please read full thread in detail. > > Mel suggested following as > > if (PageBuddy(page)) { > int nr_pages = (1 << page_order(page)) - 1; > if (PageBuddy(page)) { > nr_pages = min(nr_pages, MAX_ORDER_NR_PAGES - 1); > low_pfn += nr_pages; > continue; > } > } > > min(nr_pages, xxx) removes your concern but I think Mel's version > isn't right. It should be aligned with pageblock boundary so I > suggested following. > > if (PageBuddy(page)) { > #ifdef CONFIG_MEMORY_ISOLATION > unsigned long order = page_order(page); > if (PageBuddy(page)) { > low_pfn += (1 << order) - 1; > low_pfn = min(low_pfn, end_pfn);
Hi Minchan,
I understand now, but why use "end_pfn" here? Do you mean we should use pageblock_nr_pages instead of MAX_ORDER_NR_PAGES? Just like this:
if (PageBuddy(page)) { unsigned long order = page_order(page); order = min(order, pageblock_order); if (PageBuddy(page)) low_pfn += (1 << order) - 1; continue; }
Thanks, Xishi Qiu
> } > #endif > continue; > } > > so worst case is (pageblock_nr_pages - 1). > but we don't need to add CONFIG_MEMORY_ISOLATION so my suggestion > is following as. > > if (PageBuddy(page)) { > unsigned long order = page_order(page); > if (PageBuddy(page)) { > low_pfn += (1 << order) - 1; > low_pfn = min(low_pfn, end_pfn); > } > continue; > } > >
| |