return false;
}
+/*
+ * Returns the start pfn of the last page block in a zone. This is the starting
+ * point for full compaction of a zone. Compaction searches for free pages from
+ * the end of each zone, while isolate_freepages_block scans forward inside each
+ * page block.
+ */
+static unsigned long start_free_pfn(struct zone *zone)
+{
+ unsigned long free_pfn;
+ free_pfn = zone->zone_start_pfn + zone->spanned_pages;
+ free_pfn &= ~(pageblock_nr_pages-1);
+ return free_pfn;
+}
+
/*
* Based on information in the current compact_control, find blocks
* suitable for isolating free pages from and then isolate them.
* looking for free pages, the search will restart here as
* page migration may have returned some pages to the allocator
*/
- if (isolated)
+ if (isolated) {
high_pfn = max(high_pfn, pfn);
+
+ /*
+ * If the free scanner has wrapped, update
+ * compact_cached_free_pfn to point to the highest
+ * pageblock with free pages. This reduces excessive
+ * scanning of full pageblocks near the end of the
+ * zone
+ */
+ if (cc->order > 0 && cc->wrapped)
+ zone->compact_cached_free_pfn = high_pfn;
+ }
}
/* split_free_page does not map the pages */
cc->free_pfn = high_pfn;
cc->nr_freepages = nr_freepages;
+
+ /* If compact_cached_free_pfn is reset then set it now */
+ if (cc->order > 0 && !cc->wrapped &&
+ zone->compact_cached_free_pfn == start_free_pfn(zone))
+ zone->compact_cached_free_pfn = high_pfn;
}
/*
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
- /* Compaction run completes if the migrate and free scanner meet */
- if (cc->free_pfn <= cc->migrate_pfn)
+ /*
+ * A full (order == -1) compaction run starts at the beginning and
+ * end of a zone; it completes when the migrate and free scanner meet.
+ * A partial (order > 0) compaction can start with the free scanner
+ * at a random point in the zone, and may have to restart.
+ */
+ if (cc->free_pfn <= cc->migrate_pfn) {
+ if (cc->order > 0 && !cc->wrapped) {
+ /* We started partway through; restart at the end. */
+ unsigned long free_pfn = start_free_pfn(zone);
+ zone->compact_cached_free_pfn = free_pfn;
+ cc->free_pfn = free_pfn;
+ cc->wrapped = 1;
+ return COMPACT_CONTINUE;
+ }
+ return COMPACT_COMPLETE;
+ }
+
+ /* We wrapped around and ended up where we started. */
+ if (cc->wrapped && cc->free_pfn <= cc->start_free_pfn)
return COMPACT_COMPLETE;
/*
/* Setup to move all movable pages to the end of the zone */
cc->migrate_pfn = zone->zone_start_pfn;
- cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
- cc->free_pfn &= ~(pageblock_nr_pages-1);
+
+ if (cc->order > 0) {
+ /* Incremental compaction. Start where the last one stopped. */
+ cc->free_pfn = zone->compact_cached_free_pfn;
+ cc->start_free_pfn = cc->free_pfn;
+ } else {
+ /* Order == -1 starts at the end of the zone. */
+ cc->free_pfn = start_free_pfn(zone);
+ }
migrate_prep_local();
if (cc->order > 0) {
int ok = zone_watermark_ok(zone, cc->order,
low_wmark_pages(zone), 0, 0);
- if (ok && cc->order > zone->compact_order_failed)
+ if (ok && cc->order >= zone->compact_order_failed)
zone->compact_order_failed = cc->order + 1;
/* Currently async compaction is never deferred. */
else if (!ok && cc->sync)