On Wed, Nov 21, 2012 at 05:02:47PM +0900, Atsushi Kumagai wrote: > This patch adds the values related to buddy system to vmcoreinfo data > so that makedumpfile (dump filtering command) can filter out all free > pages with the new logic. > It's faster than the current logic because it can distinguish free page > by analyzing page structure at the same time as filtering for other > unnecessary pages (e.g. anonymous page). > OTOH, the current logic has to trace free_list to distinguish free > pages while analyzing page structure to filter out other unnecessary > pages. > > The new logic uses the fact that buddy page is marked by _mapcount == > PAGE_BUDDY_MAPCOUNT_VALUE. The values below are required to distinguish > it. > > Required values: > - OFFSET(page._mapcount) > - OFFSET(page.private) > - SIZE(pageflags) > - NUMBER(PG_slab) > - NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) > As per your explanation, you should just need to export page._mapcount offset and PAGE_BUDDY_MAPCOUNT_VALUE value so that you can figure out if a page is free or not. Why do we need rest of the three fields. - OFFSET(page.private) - SIZE(pageflags) - NUMBER(PG_slab) Thanks Vivek
