lkml.org 
[lkml]   [2009]   [Jun]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 1/2] lumpy reclaim: clean up and write lumpy reclaim
Date
> I think lumpy reclaim should be updated to meet to current split-lru.
> This patch includes bugfix and cleanup. How do you think ?
>
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> In lumpty reclaim, "cursor_page" is found just by pfn. Then, we don't know
> where "cursor" page came from. Then, putback it to "src" list is BUG.
> And as pointed out, current lumpy reclaim doens't seem to
> work as originally designed and a bit complicated. This patch adds a
> function try_lumpy_reclaim() and rewrite the logic.
>
> The major changes from current lumpy reclaim is
> - check migratetype before aggressive retry at failure.
> - check PG_unevictable at failure.
> - scan is done in buddy system order. This is a help for creating
> a lump around targeted page. We'll create a continuous pages for buddy
> allocator as far as we can _around_ reclaim target page.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
> mm/vmscan.c | 120 +++++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 71 insertions(+), 49 deletions(-)
>
> Index: mmotm-2.6.30-Jun10/mm/vmscan.c
> ===================================================================
> --- mmotm-2.6.30-Jun10.orig/mm/vmscan.c
> +++ mmotm-2.6.30-Jun10/mm/vmscan.c
> @@ -850,6 +850,69 @@ int __isolate_lru_page(struct page *page
> return ret;
> }
>
> +static int
> +try_lumpy_reclaim(struct page *page, struct list_head *dst, int request_order)
> +{
> + unsigned long buddy_base, buddy_idx, buddy_start_pfn, buddy_end_pfn;
> + unsigned long pfn, page_pfn, page_idx;
> + int zone_id, order, type;
> + int do_aggressive = 0;
> + int nr = 0;
> + /*
> + * Lumpy reqraim. Try to take near pages in requested order to
> + * create free continous pages. This algorithm tries to start
> + * from order 0 and scan buddy pages up to request_order.
> + * If you are unsure about buddy position calclation, please see
> + * mm/page_alloc.c
> + */
> + zone_id = page_zone_id(page);
> + page_pfn = page_to_pfn(page);
> + buddy_base = page_pfn & ~((1 << MAX_ORDER) - 1);
> +
> + /* Can we expect succesful reclaim ? */
> + type = get_pageblock_migratetype(page);
> + if ((type == MIGRATE_MOVABLE) || (type == MIGRATE_RECLAIMABLE))
> + do_aggressive = 1;
> +
> + for (order = 0; order < request_order; ++order) {
> + /* offset in this buddy region */
> + page_idx = page_pfn & ~buddy_base;
> + /* offset of buddy can be calculated by xor */
> + buddy_idx = page_idx ^ (1 << order);
> + buddy_start_pfn = buddy_base + buddy_idx;
> + buddy_end_pfn = buddy_start_pfn + (1 << order);
> +
> + /* scan range [buddy_start_pfn...buddy_end_pfn) */
> + for (pfn = buddy_start_pfn; pfn < buddy_end_pfn; ++pfn) {
> + /* Avoid holes within the zone. */
> + if (unlikely(!pfn_valid_within(pfn)))
> + break;
> + page = pfn_to_page(pfn);
> + /*
> + * Check that we have not crossed a zone boundary.
> + * Some arch have zones not aligned to MAX_ORDER.
> + */
> + if (unlikely(page_zone_id(page) != zone_id))
> + break;
> +
> + /* we are always under ISOLATE_BOTH */
> + if (__isolate_lru_page(page, ISOLATE_BOTH, 0) == 0) {
> + list_move(&page->lru, dst);
> + nr++;
> + } else if (do_aggressive && !PageUnevictable(page))

Could you explain this branch intention more?



> + continue;
> + else
> + break;
> + }
> + /* we can't refill this order */
> + if (pfn != buddy_end_pfn)
> + break;
> + if (buddy_start_pfn < page_pfn)
> + page_pfn = buddy_start_pfn;
> + }
> + return nr;




\
 
 \ /
  Last update: 2009-06-10 08:13    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site