[PATCH 4/8] Scanner changes needed to implement per-container scanner

[Pavel Emelianov <xemul@openvz.org>]

The core change is that the isolate_lru_pages() call is
replaced with struct scan_controll->isolate_pages() call.

Other changes include exporting __isolate_lru_page() for
per-container isolator and handling variable-to-pointer
changes in try_to_free_pages().

This makes possible to use different isolation routines
for per-container page reclamation. This will be used by
the following patch.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

diff -upr linux-2.6.22-rc2-mm1.orig/include/linux/swap.h linux-2.6.22-rc2-mm1-2/include/linux/swap.h
--- linux-2.6.22-rc2-mm1.orig/include/linux/swap.h	2007-05-30 12:32:36.000000000 +0400
+++ linux-2.6.22-rc2-mm1-2/include/linux/swap.h	2007-06-01 16:35:13.000000000 +0400
@@ -192,6 +192,11 @@ extern void swap_setup(void);
 /* linux/mm/vmscan.c */
 extern unsigned long try_to_free_pages(struct zone **zones, int order,
 					gfp_t gfp_mask);
+
+struct rss_container;
+extern unsigned long try_to_free_pages_in_container(struct rss_container *);
+int __isolate_lru_page(struct page *page, int mode);
+
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
 extern int remove_mapping(struct address_space *mapping, struct page *page);
diff -upr linux-2.6.22-rc2-mm1.orig/mm/vmscan.c linux-2.6.22-rc2-mm1-2/mm/vmscan.c
--- linux-2.6.22-rc2-mm1.orig/mm/vmscan.c	2007-05-30 12:32:36.000000000 +0400
+++ linux-2.6.22-rc2-mm1-2/mm/vmscan.c	2007-06-01 16:35:15.000000000 +0400
@@ -47,6 +47,8 @@
 
 #include "internal.h"
 
+#include <linux/rss_container.h>
+
 struct scan_control {
 	/* Incremented by the number of inactive pages that were scanned */
 	unsigned long nr_scanned;
@@ -70,6 +72,13 @@ struct scan_control {
 	int all_unreclaimable;
 
 	int order;
+
+	struct rss_container *container;
+
+	unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
+			unsigned long *scanned, int order, int mode,
+			struct zone *zone, struct rss_container *cont,
+			int active);
 };
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -622,7 +631,7 @@ keep:
  *
  * returns 0 on success, -ve errno on failure.
  */
-static int __isolate_lru_page(struct page *page, int mode)
+int __isolate_lru_page(struct page *page, int mode)
 {
 	int ret = -EINVAL;
 
@@ -774,6 +783,19 @@ static unsigned long clear_active_flags(
 	return nr_active;
 }
 
+static unsigned long isolate_pages_global(unsigned long nr,
+		struct list_head *dst, unsigned long *scanned,
+		int order, int mode, struct zone *z,
+		struct rss_container *cont, int active)
+{
+	if (active)
+		return isolate_lru_pages(nr, &z->active_list,
+				dst, scanned, order, mode);
+	else
+		return isolate_lru_pages(nr, &z->inactive_list,
+				dst, scanned, order, mode);
+}
+
 /*
  * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
  * of reclaimed pages
@@ -797,11 +819,11 @@ static unsigned long shrink_inactive_lis
 		unsigned long nr_freed;
 		unsigned long nr_active;
 
-		nr_taken = isolate_lru_pages(sc->swap_cluster_max,
-			     &zone->inactive_list,
-			     &page_list, &nr_scan, sc->order,
-			     (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
-					     ISOLATE_BOTH : ISOLATE_INACTIVE);
+		nr_taken = sc->isolate_pages(sc->swap_cluster_max, &page_list,
+				&nr_scan, sc->order,
+				(sc->order > PAGE_ALLOC_COSTLY_ORDER) ?
+					ISOLATE_BOTH : ISOLATE_INACTIVE,
+				zone, sc->container, 0);
 		nr_active = clear_active_flags(&page_list);
 
 		__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
@@ -950,8 +975,8 @@ force_reclaim_mapped:
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);
-	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
-			    &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE);
+	pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned,
+			sc->order, ISOLATE_ACTIVE, zone, sc->container, 1);
 	zone->pages_scanned += pgscanned;
 	__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
@@ -1142,7 +1169,8 @@ static unsigned long shrink_zones(int pr
  * holds filesystem locks which prevent writeout this might not work, and the
  * allocation attempt will fail.
  */
-unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
+unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
+		struct scan_control *sc)
 {
 	int priority;
 	int ret = 0;
@@ -1151,14 +1179,6 @@ unsigned long try_to_free_pages(struct z
 	struct reclaim_state *reclaim_state = current->reclaim_state;
 	unsigned long lru_pages = 0;
 	int i;
-	struct scan_control sc = {
-		.gfp_mask = gfp_mask,
-		.may_writepage = !laptop_mode,
-		.swap_cluster_max = SWAP_CLUSTER_MAX,
-		.may_swap = 1,
-		.swappiness = vm_swappiness,
-		.order = order,
-	};
 
 	delay_swap_prefetch();
 	count_vm_event(ALLOCSTALL);
@@ -1174,17 +1194,23 @@ unsigned long try_to_free_pages(struct z
 	}
 
 	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
-		sc.nr_scanned = 0;
+		sc->nr_scanned = 0;
 		if (!priority)
 			disable_swap_token();
-		nr_reclaimed += shrink_zones(priority, zones, &sc);
-		shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
+		nr_reclaimed += shrink_zones(priority, zones, sc);
+		if (sc->container == NULL)
+			/*
+			 * we do not shrink slabs as this won't unmap any
+			 * pages from user and thus won't help him to charge
+			 * more pages  --xemul
+			 */
+			shrink_slab(sc->nr_scanned, gfp_mask, lru_pages);
 		if (reclaim_state) {
 			nr_reclaimed += reclaim_state->reclaimed_slab;
 			reclaim_state->reclaimed_slab = 0;
 		}
-		total_scanned += sc.nr_scanned;
-		if (nr_reclaimed >= sc.swap_cluster_max) {
+		total_scanned += sc->nr_scanned;
+		if (nr_reclaimed >= sc->swap_cluster_max) {
 			ret = 1;
 			goto out;
 		}
@@ -1196,18 +1222,23 @@ unsigned long try_to_free_pages(struct z
 		 * that's undesirable in laptop mode, where we *want* lumpy
 		 * writeout.  So in laptop mode, write out the whole world.
 		 */
-		if (total_scanned > sc.swap_cluster_max +
-					sc.swap_cluster_max / 2) {
+		if (total_scanned > sc->swap_cluster_max +
+					sc->swap_cluster_max / 2) {
 			wakeup_pdflush(laptop_mode ? 0 : total_scanned);
-			sc.may_writepage = 1;
+			sc->may_writepage = 1;
 		}
 
 		/* Take a nap, wait for some writeback to complete */
-		if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
+		if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
 			congestion_wait(WRITE, HZ/10);
 	}
-	/* top priority shrink_caches still had more to do? don't OOM, then */
-	if (!sc.all_unreclaimable)
+	/*
+	 * top priority shrink_caches still had more to do? don't OOM, then
+	 *
+	 * we cannot hope shrink_caches to help us in case we are trying
+	 * to shrink container pages  --xemul
+	 */
+	if (!sc->all_unreclaimable && sc->container == NULL)
 		ret = 1;
 out:
 	/*
@@ -1230,6 +1261,22 @@ out:
 	return ret;
 }
 
+unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
+{
+	struct scan_control sc = {
+		.gfp_mask = gfp_mask,
+		.may_writepage = !laptop_mode,
+		.swap_cluster_max = SWAP_CLUSTER_MAX,
+		.may_swap = 1,
+		.swappiness = vm_swappiness,
+		.order = order,
+		.container = NULL,
+		.isolate_pages = isolate_pages_global,
+	};
+
+	return do_try_to_free_pages(zones, gfp_mask, &sc);
+}
+
 /*
  * For kswapd, balance_pgdat() will work across all this node's zones until
  * they are all at pages_high.
@@ -1265,6 +1347,8 @@ static unsigned long balance_pgdat(pg_da
 		.swap_cluster_max = SWAP_CLUSTER_MAX,
 		.swappiness = vm_swappiness,
 		.order = order,
+		.container = NULL,
+		.isolate_pages = isolate_pages_global,
 	};
 	/*
 	 * temp_priority is used to remember the scanning priority at which
@@ -1604,6 +1688,8 @@ unsigned long shrink_all_memory(unsigned
 		.swap_cluster_max = nr_pages,
 		.may_writepage = 1,
 		.swappiness = vm_swappiness,
+		.container = NULL,
+		.isolate_pages = isolate_pages_global,
 	};
 
 	delay_swap_prefetch();
@@ -1789,6 +1875,8 @@ static int __zone_reclaim(struct zone *z
 					SWAP_CLUSTER_MAX),
 		.gfp_mask = gfp_mask,
 		.swappiness = vm_swappiness,
+		.container = NULL,
+		.isolate_pages = isolate_pages_global,
 	};
 	unsigned long slab_reclaimable;
 

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/