[PATCH] 4/4: incremental min aware kswapd

Nick Piggin
2004-08-06T05:04:24Z

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4/4

[-- Attachment #2: vm-kswapd-incmin.patch --]
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Explicitly teach kswapd about the incremental min logic instead of just scanning
all zones under the first low zone. This should keep more even pressure applied
on the zones.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>

---

linux-2.6-npiggin/mm/vmscan.c | 98 +++++++++++++++++-------------------------
1 files changed, 40 insertions(+), 58 deletions(-)

diff -puN mm/vmscan.c~vm-kswapd-incmin mm/vmscan.c
--- linux-2.6/mm/vmscan.c~vm-kswapd-incmin 2004-08-06 14:49:48.000000000 +1000
+++ linux-2.6-npiggin/mm/vmscan.c 2004-08-06 14:49:48.000000000 +1000
@@ -1011,80 +1011,63 @@ static int balance_pgdat(pg_data_t *pgda

for (priority = DEF_PRIORITY; priority >= 0; priority--) {
int all_zones_ok = 1;
- int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long lru_pages = 0;
+ int first_low = 0;

- 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;
+ sc.nr_scanned = 0;
+ sc.nr_reclaimed = 0;

- if (zone->all_unreclaimable &&
- priority != DEF_PRIORITY)
- continue;
-
- if (zone->free_pages <= zone->pages_high) {
- end_zone = i;
- goto scan;
- }
- }
- goto out;
- } else {
- end_zone = pgdat->nr_zones - 1;
- }
-scan:
- for (i = 0; i <= end_zone; i++) {
+ /* Scan in the highmem->dma direction */
+ for (i = pgdat->nr_zones - 1; i >= 0; i--) {
struct zone *zone = pgdat->node_zones + i;

- lru_pages += zone->nr_active + zone->nr_inactive;
- }
+ if (nr_pages == 0) { /* Not software suspend */
+ unsigned long pgfree = zone->free_pages;
+ unsigned long pghigh = zone->pages_high;

- /*
- * Now scan the zone in the dma->highmem direction, stopping
- * at the last zone which needs scanning.
- *
- * We do this because the page allocator works in the opposite
- * direction. This prevents the page allocator from allocating
- * pages behind kswapd's direction of progress, which would
- * cause too much scanning of the lower zones.
- */
- for (i = 0; i <= end_zone; i++) {
- struct zone *zone = pgdat->node_zones + i;
+ /*
+ * This satisfies the "incremental min" or
+ * lower zone protection logic in the allocator
+ */
+ if (first_low > i)
+ pghigh += zone->protection[first_low];
+ if (pgfree >= pghigh)
+ continue;
+ if (first_low < i)
+ first_low = i;
+
+ all_zones_ok = 0;
+ sc.nr_to_reclaim = pghigh - pgfree;
+ } else
+ sc.nr_to_reclaim = INT_MAX; /* Software susp */

if (zone->all_unreclaimable && priority != DEF_PRIORITY)
continue;
-
- if (nr_pages == 0) { /* Not software suspend */
- if (zone->free_pages <= zone->pages_high)
- all_zones_ok = 0;
- }
zone->temp_priority = priority;
if (zone->prev_priority > priority)
zone->prev_priority = priority;
- sc.nr_scanned = 0;
- sc.nr_reclaimed = 0;
sc.priority = priority;
+ lru_pages += zone->nr_active + zone->nr_inactive;
shrink_zone(zone, &sc);
- reclaim_state->reclaimed_slab = 0;
- shrink_slab(sc.nr_scanned, GFP_KERNEL, lru_pages);
- sc.nr_reclaimed += reclaim_state->reclaimed_slab;
- total_reclaimed += sc.nr_reclaimed;
- if (zone->all_unreclaimable)
- continue;
if (zone->pages_scanned > zone->present_pages * 2)
zone->all_unreclaimable = 1;
- /*
- * If we've done a decent amount of scanning and
- * the reclaim ratio is low, start doing writepage
- * even in laptop mode
- */
- if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
- total_scanned > total_reclaimed+total_reclaimed/2)
- sc.may_writepage = 1;
}
+ reclaim_state->reclaimed_slab = 0;
+ shrink_slab(sc.nr_scanned, GFP_KERNEL, lru_pages);
+ sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+
+ total_reclaimed += sc.nr_reclaimed;
+ total_scanned += sc.nr_scanned;
+
+ /*
+ * If we've done a decent amount of scanning and
+ * the reclaim ratio is low, start doing writepage
+ * even in laptop mode
+ */
+ if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
+ total_scanned > total_reclaimed+total_reclaimed/2)
+ sc.may_writepage = 1;
+
if (nr_pages && to_free > total_reclaimed)
continue; /* swsusp: need to do more work */
if (all_zones_ok)
@@ -1096,7 +1079,6 @@ scan:
if (total_scanned && priority < DEF_PRIORITY - 2)
blk_congestion_wait(WRITE, HZ/10);
}
-out:
for (i = 0; i < pgdat->nr_zones; i++) {
struct zone *zone = pgdat->node_zones + i;

_