[PATCH] swsusp reclaim tweaks 2

[Con Kolivas <kernel@kolivas.org>]

On Fri, 17 Mar 2006 03:46 pm, Con Kolivas wrote:
> On Fri, 17 Mar 2006 03:28 pm, Con Kolivas wrote:
> > Ok here is a kind of directed memory reclaim for swsusp which is
> > different to ordinary memory reclaim. It reclaims memory in up to 4
> > passes with just shrink_zone, without hooking into balance_pgdat thereby
> > simplifying that function as well.

> It may need to be made more aggressive with another reclaim mapped pass to
> ensure it frees enough memory. That would be trivial to add.

Indeed this was true after a few more suspend resume cycles. Here is a rework
which survived many suspend resume cycles. This worked nicely in combination
with the aggressive swap prefetch tunable being set on resume.

Ok, now please test :) Patch for 2.6.16-rc6-mm1

Cheers,
Con
---
 kernel/power/swsusp.c |   10 +--
 mm/vmscan.c           |  145 ++++++++++++++++++++++++++++----------------------
 2 files changed, 87 insertions(+), 68 deletions(-)

Index: linux-2.6.16-rc6-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.16-rc6-mm1.orig/mm/vmscan.c	2006-03-17 16:44:47.000000000 +1100
+++ linux-2.6.16-rc6-mm1/mm/vmscan.c	2006-03-17 16:57:33.000000000 +1100
@@ -74,6 +74,15 @@ struct scan_control {
 	 * In this context, it doesn't matter that we scan the
 	 * whole list at once. */
 	int swap_cluster_max;
+
+	/*
+	 * If we're doing suspend to disk, what pass is this.
+	 * 3 = Reclaim from inactive_list only
+	 * 2 = Reclaim from active list but don't reclaim mapped
+	 * 1 = 2nd pass of type 2
+	 * 0 = Reclaim mapped
+	 */
+	int suspend;
 };
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -1345,7 +1354,7 @@ static unsigned long shrink_zone(int pri
 	 */
 	zone->nr_scan_active += (zone->nr_active >> priority) + 1;
 	nr_active = zone->nr_scan_active;
-	if (nr_active >= sc->swap_cluster_max)
+	if (nr_active >= sc->swap_cluster_max && sc->suspend < 3)
 		zone->nr_scan_active = 0;
 	else
 		nr_active = 0;
@@ -1402,6 +1411,7 @@ static unsigned long shrink_zones(int pr
 	unsigned long nr_reclaimed = 0;
 	int i;
 
+	sc->suspend = 0;
 	for (i = 0; zones[i] != NULL; i++) {
 		struct zone *zone = zones[i];
 
@@ -1422,7 +1432,12 @@ static unsigned long shrink_zones(int pr
 	}
 	return nr_reclaimed;
 }
- 
+
+#define for_each_priority(priority)	\
+	for (priority = DEF_PRIORITY;	\
+		priority >= 0;		\
+		priority--)
+
 /*
  * This is the main entry point to direct page reclaim.
  *
@@ -1466,7 +1481,7 @@ unsigned long try_to_free_pages(struct z
 		lru_pages += zone->nr_active + zone->nr_inactive;
 	}
 
-	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+	for_each_priority(priority) {
 		sc.nr_mapped = read_page_state(nr_mapped);
 		sc.nr_scanned = 0;
 		if (!priority)
@@ -1516,10 +1531,6 @@ out:
  * For kswapd, balance_pgdat() will work across all this node's zones until
  * they are all at pages_high.
  *
- * If `nr_pages' is non-zero then it is the number of pages which are to be
- * reclaimed, regardless of the zone occupancies.  This is a software suspend
- * special.
- *
  * Returns the number of pages which were actually freed.
  *
  * There is special handling here for zones which are full of pinned pages.
@@ -1537,10 +1548,8 @@ out:
  * the page allocator fallback scheme to ensure that aging of pages is balanced
  * across the zones.
  */
-static unsigned long balance_pgdat(pg_data_t *pgdat, unsigned long nr_pages,
-				int order)
+static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
 {
-	unsigned long to_free = nr_pages;
 	int all_zones_ok;
 	int priority;
 	int i;
@@ -1550,7 +1559,8 @@ static unsigned long balance_pgdat(pg_da
 	struct scan_control sc = {
 		.gfp_mask = GFP_KERNEL,
 		.may_swap = 1,
-		.swap_cluster_max = nr_pages ? nr_pages : SWAP_CLUSTER_MAX,
+		.swap_cluster_max = SWAP_CLUSTER_MAX,
+		.suspend = 0,
 	};
 
 loop_again:
@@ -1567,7 +1577,7 @@ loop_again:
 		zone->temp_priority = DEF_PRIORITY;
 	}
 
-	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+	for_each_priority(priority) {
 		int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */
 		unsigned long lru_pages = 0;
 
@@ -1577,31 +1587,27 @@ loop_again:
 
 		all_zones_ok = 1;
 
-		if (nr_pages == 0) {
-			/*
-			 * Scan in the highmem->dma direction for the highest
-			 * zone which needs scanning
-			 */
-			for (i = pgdat->nr_zones - 1; i >= 0; i--) {
-				struct zone *zone = pgdat->node_zones + i;
+		/*
+		 * Scan in the highmem->dma direction for the highest
+		 * zone which needs scanning
+		 */
+		for (i = pgdat->nr_zones - 1; i >= 0; i--) {
+			struct zone *zone = pgdat->node_zones + i;
 
-				if (!populated_zone(zone))
-					continue;
+			if (!populated_zone(zone))
+				continue;
 
-				if (zone->all_unreclaimable &&
-						priority != DEF_PRIORITY)
-					continue;
+			if (zone->all_unreclaimable &&
+					priority != DEF_PRIORITY)
+				continue;
 
-				if (!zone_watermark_ok(zone, order,
-						zone->pages_high, 0, 0)) {
-					end_zone = i;
-					goto scan;
-				}
+			if (!zone_watermark_ok(zone, order,
+					zone->pages_high, 0, 0)) {
+				end_zone = i;
+				goto scan;
 			}
-			goto out;
-		} else {
-			end_zone = pgdat->nr_zones - 1;
 		}
+		goto out;
 scan:
 		for (i = 0; i <= end_zone; i++) {
 			struct zone *zone = pgdat->node_zones + i;
@@ -1628,11 +1634,9 @@ scan:
 			if (zone->all_unreclaimable && priority != DEF_PRIORITY)
 				continue;
 
-			if (nr_pages == 0) {	/* Not software suspend */
-				if (!zone_watermark_ok(zone, order,
-						zone->pages_high, end_zone, 0))
-					all_zones_ok = 0;
-			}
+			if (!zone_watermark_ok(zone, order,
+					zone->pages_high, end_zone, 0))
+				all_zones_ok = 0;
 			zone->temp_priority = priority;
 			if (zone->prev_priority > priority)
 				zone->prev_priority = priority;
@@ -1657,8 +1661,6 @@ scan:
 			    total_scanned > nr_reclaimed + nr_reclaimed / 2)
 				sc.may_writepage = 1;
 		}
-		if (nr_pages && to_free > nr_reclaimed)
-			continue;	/* swsusp: need to do more work */
 		if (all_zones_ok)
 			break;		/* kswapd: all done */
 		/*
@@ -1674,7 +1676,7 @@ scan:
 		 * matches the direct reclaim path behaviour in terms of impact
 		 * on zone->*_priority.
 		 */
-		if ((nr_reclaimed >= SWAP_CLUSTER_MAX) && !nr_pages)
+		if ((nr_reclaimed >= SWAP_CLUSTER_MAX))
 			break;
 	}
 out:
@@ -1756,7 +1758,7 @@ static int kswapd(void *p)
 		}
 		finish_wait(&pgdat->kswapd_wait, &wait);
 
-		balance_pgdat(pgdat, 0, order);
+		balance_pgdat(pgdat, order);
 	}
 	return 0;
 }
@@ -1790,32 +1792,52 @@ void wakeup_kswapd(struct zone *zone, in
  */
 unsigned long shrink_all_memory(unsigned long nr_pages)
 {
-	pg_data_t *pgdat;
-	unsigned long nr_to_free = nr_pages;
 	unsigned long ret = 0;
-	unsigned retry = 2;
-	struct reclaim_state reclaim_state = {
-		.reclaimed_slab = 0,
+	struct scan_control sc = {
+		.gfp_mask = GFP_KERNEL,
+		.may_swap = 1,
+		.swap_cluster_max = nr_pages,
+		.suspend = 3,
+		.may_writepage = 1,
 	};
 
 	delay_swap_prefetch();
 
-	current->reclaim_state = &reclaim_state;
-repeat:
-	for_each_online_pgdat(pgdat) {
-		unsigned long freed;
+	do {
+		int priority;
 
-		freed = balance_pgdat(pgdat, nr_to_free, 0);
-		ret += freed;
-		nr_to_free -= freed;
-		if ((long)nr_to_free <= 0)
-			break;
-	}
-	if (retry-- && ret < nr_pages) {
-		blk_congestion_wait(WRITE, HZ/5);
-		goto repeat;
-	}
-	current->reclaim_state = NULL;
+		for_each_priority(priority) {
+			struct zone *zone;
+			unsigned long lru_pages = 0;
+
+			for_each_zone(zone) {
+				unsigned long freed;
+
+				if (!populated_zone(zone))
+					continue;
+
+				if (zone->all_unreclaimable &&
+				    priority != DEF_PRIORITY)
+					continue;
+
+				lru_pages += zone->nr_active +
+					zone->nr_inactive;
+				/*
+				 * shrink_active_list needs this to reclaim
+				 * mapped pages
+				 */
+				if (!sc.suspend)
+					zone->prev_priority = 0;
+				freed = shrink_zone(priority, zone, &sc);
+				ret += freed;
+				if (ret > nr_pages)
+					goto out;
+				}
+			shrink_slab(0, sc.gfp_mask, lru_pages);
+			blk_congestion_wait(WRITE, HZ / 5);
+		}
+	} while (--sc.suspend >= 0);
+out:
 	return ret;
 }
 #endif
@@ -1913,6 +1935,7 @@ static int __zone_reclaim(struct zone *z
 		.swap_cluster_max = max_t(unsigned long, nr_pages,
 					SWAP_CLUSTER_MAX),
 		.gfp_mask = gfp_mask,
+		.suspend = 0,
 	};
 
 	disable_swap_token();
Index: linux-2.6.16-rc6-mm1/kernel/power/swsusp.c
===================================================================
--- linux-2.6.16-rc6-mm1.orig/kernel/power/swsusp.c	2006-03-17 16:44:47.000000000 +1100
+++ linux-2.6.16-rc6-mm1/kernel/power/swsusp.c	2006-03-17 16:45:11.000000000 +1100
@@ -173,9 +173,6 @@ void free_all_swap_pages(int swap, struc
  *	Notice: all userland should be stopped before it is called, or
  *	livelock is possible.
  */
-
-#define SHRINK_BITE	10000
-
 int swsusp_shrink_memory(void)
 {
 	long size, tmp;
@@ -195,13 +192,12 @@ int swsusp_shrink_memory(void)
 			if (!is_highmem(zone))
 				tmp -= zone->free_pages;
 		if (tmp > 0) {
-			tmp = shrink_all_memory(SHRINK_BITE);
+			tmp = shrink_all_memory(tmp);
 			if (!tmp)
 				return -ENOMEM;
 			pages += tmp;
-		} else if (size > image_size / PAGE_SIZE) {
-			tmp = shrink_all_memory(SHRINK_BITE);
-			pages += tmp;
+			if (pages > size)
+				break;
 		}
 		printk("\b%c", p[i++%4]);
 	} while (tmp > 0);