RFC: Speed freeing memory for suspend.

RFC: Speed freeing memory for suspend.

[Nigel Cunningham]

Hi all.

Here's a patch I've prepared which improves the speed at which memory is
freed prior to suspend. It should be a big gain for swsusp. For
suspend2, it isn't used much, but has shown big improvements when I set
a very low image size limit and had memory quite full.

Regards,

Nigel

diff -ruNp 898-swap_cluster_max_adjustments-old/mm/vmscan.c 898-swap_cluster_max_adjustments-new/mm/vmscan.c
--- 898-swap_cluster_max_adjustments-old/mm/vmscan.c	2005-03-03 12:04:12.000000000 +1100
+++ 898-swap_cluster_max_adjustments-new/mm/vmscan.c	2005-03-03 11:51:00.000000000 +1100
@@ -73,6 +73,12 @@ struct scan_control {
 	unsigned int gfp_mask;
 
 	int may_writepage;
+
+	/* This context's SWAP_CLUSTER_MAX. If freeing memory for
+	 * suspend, we effectively ignore SWAP_CLUSTER_MAX.
+	 * In this context, it doesn't matter that we scan the
+	 * whole list at once. */
+	int swap_cluster_max;
 };
 
 #ifdef CONFIG_MKI
@@ -566,7 +572,7 @@ static void shrink_cache(struct zone *zo
 		int nr_scan = 0;
 		int nr_freed;
 
-		while (nr_scan++ < SWAP_CLUSTER_MAX &&
+		while (nr_scan++ < sc->swap_cluster_max &&
 				!list_empty(&zone->inactive_list)) {
 			page = lru_to_page(&zone->inactive_list);
 
@@ -811,31 +817,31 @@ shrink_zone(struct zone *zone, struct sc
 	 */
 	zone->nr_scan_active += (zone->nr_active >> sc->priority) + 1;
 	nr_active = zone->nr_scan_active;
-	if (nr_active >= SWAP_CLUSTER_MAX)
+	if (nr_active >= sc->swap_cluster_max)
 		zone->nr_scan_active = 0;
 	else
 		nr_active = 0;
 
 	zone->nr_scan_inactive += (zone->nr_inactive >> sc->priority) + 1;
 	nr_inactive = zone->nr_scan_inactive;
-	if (nr_inactive >= SWAP_CLUSTER_MAX)
+	if (nr_inactive >= sc->swap_cluster_max)
 		zone->nr_scan_inactive = 0;
 	else
 		nr_inactive = 0;
 
-	sc->nr_to_reclaim = SWAP_CLUSTER_MAX;
+	sc->nr_to_reclaim = sc->swap_cluster_max;
 
 	while (nr_active || nr_inactive) {
 		if (nr_active) {
 			sc->nr_to_scan = min(nr_active,
-					(unsigned long)SWAP_CLUSTER_MAX);
+					(unsigned long)sc->swap_cluster_max);
 			nr_active -= sc->nr_to_scan;
 			refill_inactive_zone(zone, sc);
 		}
 
 		if (nr_inactive) {
 			sc->nr_to_scan = min(nr_inactive,
-					(unsigned long)SWAP_CLUSTER_MAX);
+					(unsigned long)sc->swap_cluster_max);
 			nr_inactive -= sc->nr_to_scan;
 			shrink_cache(zone, sc);
 			if (sc->nr_to_reclaim <= 0)
@@ -936,13 +942,14 @@ int try_to_free_pages(struct zone **zone
 		sc.nr_scanned = 0;
 		sc.nr_reclaimed = 0;
 		sc.priority = priority;
+		sc.swap_cluster_max = SWAP_CLUSTER_MAX;
 		shrink_caches(zones, &sc);
 		shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
 		if (reclaim_state) {
 			sc.nr_reclaimed += reclaim_state->reclaimed_slab;
 			reclaim_state->reclaimed_slab = 0;
 		}
-		if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) {
+		if (sc.nr_reclaimed >= sc.swap_cluster_max) {
 			ret = 1;
 			goto out;
 		}
@@ -956,7 +963,7 @@ int try_to_free_pages(struct zone **zone
 		 * that's undesirable in laptop mode, where we *want* lumpy
 		 * writeout.  So in laptop mode, write out the whole world.
 		 */
-		if (total_scanned > SWAP_CLUSTER_MAX + SWAP_CLUSTER_MAX/2) {
+		if (total_scanned > sc.swap_cluster_max + sc.swap_cluster_max/2) {
 			wakeup_bdflush(laptop_mode ? 0 : total_scanned);
 			sc.may_writepage = 1;
 		}
@@ -1091,6 +1098,7 @@ scan:
 			sc.nr_scanned = 0;
 			sc.nr_reclaimed = 0;
 			sc.priority = priority;
+			sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX;
 			shrink_zone(zone, &sc);
 			reclaim_state->reclaimed_slab = 0;
 			shrink_slab(sc.nr_scanned, GFP_KERNEL, lru_pages);
@@ -1128,7 +1136,7 @@ scan:
 		 * matches the direct reclaim path behaviour in terms of impact
 		 * on zone->*_priority.
 		 */
-		if (total_reclaimed >= SWAP_CLUSTER_MAX)
+		if ((total_reclaimed >= SWAP_CLUSTER_MAX) && (!nr_pages))
 			break;
 	}
 out:

-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com
Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028;  Mob: +61 (417) 100 574

Maintainer of Suspend2 Kernel Patches http://softwaresuspend.berlios.de


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Re: RFC: Speed freeing memory for suspend.

[Pavel Machek]

Hi!

> Here's a patch I've prepared which improves the speed at which memory is
> freed prior to suspend. It should be a big gain for swsusp. For
> suspend2, it isn't used much, but has shown big improvements when I set
> a very low image size limit and had memory quite full.

It looks good to me.
								Pavel

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Re: RFC: Speed freeing memory for suspend.

[Stefan Voelkel]

Hello,

I tried to do something similar, if not in code but effekt, for apm -s, but
it did not work and my mail was unanswered:

  http://marc.theaimsgroup.com/?l=linux-mm&m=110779400803717&w=2

regards
  Stefan

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Re: RFC: Speed freeing memory for suspend.

[Nigel Cunningham]

Hi.

They're actually quite different, so far as I can see. My patch simply
increases the number of pages that the VM scans in one go. It doesn't
use allocation to create additional VM pressure.

Regards,

Nigel

On Tue, 2005-03-08 at 00:22, Stefan Voelkel wrote:
> Hello,
> 
> I tried to do something similar, if not in code but effekt, for apm -s, but
> it did not work and my mail was unanswered:
> 
>   http://marc.theaimsgroup.com/?l=linux-mm&m=110779400803717&w=2
> 
> regards
>   Stefan
-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com
Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028;  Mob: +61 (417) 100 574

Maintainer of Suspend2 Kernel Patches http://softwaresuspend.berlios.de


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