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authorLee Schermerhorn <Lee.Schermerhorn@hp.com>2008-10-18 23:26:39 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 11:50:26 -0400
commit894bc310419ac95f4fa4142dc364401a7e607f65 (patch)
tree15d56a7333b41620016b845d2323dd06e822b621 /include/linux/swap.h
parent8a7a8544a4f6554ec2d8048ac9f9672f442db5a2 (diff)
Unevictable LRU Infrastructure
When the system contains lots of mlocked or otherwise unevictable pages, the pageout code (kswapd) can spend lots of time scanning over these pages. Worse still, the presence of lots of unevictable pages can confuse kswapd into thinking that more aggressive pageout modes are required, resulting in all kinds of bad behaviour. Infrastructure to manage pages excluded from reclaim--i.e., hidden from vmscan. Based on a patch by Larry Woodman of Red Hat. Reworked to maintain "unevictable" pages on a separate per-zone LRU list, to "hide" them from vmscan. Kosaki Motohiro added the support for the memory controller unevictable lru list. Pages on the unevictable list have both PG_unevictable and PG_lru set. Thus, PG_unevictable is analogous to and mutually exclusive with PG_active--it specifies which LRU list the page is on. The unevictable infrastructure is enabled by a new mm Kconfig option [CONFIG_]UNEVICTABLE_LRU. A new function 'page_evictable(page, vma)' in vmscan.c tests whether or not a page may be evictable. Subsequent patches will add the various !evictable tests. We'll want to keep these tests light-weight for use in shrink_active_list() and, possibly, the fault path. To avoid races between tasks putting pages [back] onto an LRU list and tasks that might be moving the page from non-evictable to evictable state, the new function 'putback_lru_page()' -- inverse to 'isolate_lru_page()' -- tests the "evictability" of a page after placing it on the LRU, before dropping the reference. If the page has become unevictable, putback_lru_page() will redo the 'putback', thus moving the page to the unevictable list. This way, we avoid "stranding" evictable pages on the unevictable list. [akpm@linux-foundation.org: fix fallout from out-of-order merge] [riel@redhat.com: fix UNEVICTABLE_LRU and !PROC_PAGE_MONITOR build] [nishimura@mxp.nes.nec.co.jp: remove redundant mapping check] [kosaki.motohiro@jp.fujitsu.com: unevictable-lru-infrastructure: putback_lru_page()/unevictable page handling rework] [kosaki.motohiro@jp.fujitsu.com: kill unnecessary lock_page() in vmscan.c] [kosaki.motohiro@jp.fujitsu.com: revert migration change of unevictable lru infrastructure] [kosaki.motohiro@jp.fujitsu.com: revert to unevictable-lru-infrastructure-kconfig-fix.patch] [kosaki.motohiro@jp.fujitsu.com: restore patch failure of vmstat-unevictable-and-mlocked-pages-vm-events.patch] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Debugged-by: Benjamin Kidwell <benjkidwell@yahoo.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/swap.h')
-rw-r--r--include/linux/swap.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 7d09d79997a4..a2113044d20a 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -180,6 +180,8 @@ extern int lru_add_drain_all(void);
180extern void rotate_reclaimable_page(struct page *page); 180extern void rotate_reclaimable_page(struct page *page);
181extern void swap_setup(void); 181extern void swap_setup(void);
182 182
183extern void add_page_to_unevictable_list(struct page *page);
184
183/** 185/**
184 * lru_cache_add: add a page to the page lists 186 * lru_cache_add: add a page to the page lists
185 * @page: the page to add 187 * @page: the page to add
@@ -228,6 +230,16 @@ static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
228} 230}
229#endif 231#endif
230 232
233#ifdef CONFIG_UNEVICTABLE_LRU
234extern int page_evictable(struct page *page, struct vm_area_struct *vma);
235#else
236static inline int page_evictable(struct page *page,
237 struct vm_area_struct *vma)
238{
239 return 1;
240}
241#endif
242
231extern int kswapd_run(int nid); 243extern int kswapd_run(int nid);
232 244
233#ifdef CONFIG_MMU 245#ifdef CONFIG_MMU