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authorMel Gorman <mgorman@suse.de>2012-10-08 16:32:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:50 +0900
commit753341a4b85ff337487b9959c71c529f522004f4 (patch)
tree6a705fd73dd599e7eeb58cb06e84c86c07c03a64
parentf40d1e42bb988d2a26e8e111ea4c4c7bac819b7e (diff)
revert "mm: have order > 0 compaction start off where it left"
This reverts commit 7db8889ab05b ("mm: have order > 0 compaction start off where it left") and commit de74f1cc ("mm: have order > 0 compaction start near a pageblock with free pages"). These patches were a good idea and tests confirmed that they massively reduced the amount of scanning but the implementation is complex and tricky to understand. A later patch will cache what pageblocks should be skipped and reimplements the concept of compact_cached_free_pfn on top for both migration and free scanners. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/mmzone.h4
-rw-r--r--mm/compaction.c65
-rw-r--r--mm/internal.h6
-rw-r--r--mm/page_alloc.c5
4 files changed, 5 insertions, 75 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 85ac67aa577..16a4cc2950a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -369,10 +369,6 @@ struct zone {
*/
spinlock_t lock;
int all_unreclaimable; /* All pages pinned */
-#if defined CONFIG_COMPACTION || defined CONFIG_CMA
- /* pfn where the last incremental compaction isolated free pages */
- unsigned long compact_cached_free_pfn;
-#endif
#ifdef CONFIG_MEMORY_HOTPLUG
/* see spanned/present_pages for more description */
seqlock_t span_seqlock;
diff --git a/mm/compaction.c b/mm/compaction.c
index bdf6e13045e..db76361a311 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -538,20 +538,6 @@ next_pageblock:
#endif /* CONFIG_COMPACTION || CONFIG_CMA */
#ifdef CONFIG_COMPACTION
/*
- * 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.
*/
@@ -619,19 +605,8 @@ static void isolate_freepages(struct zone *zone,
* 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 */
@@ -639,11 +614,6 @@ static void isolate_freepages(struct zone *zone,
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;
}
/*
@@ -738,26 +708,8 @@ static int compact_finished(struct zone *zone,
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
- /*
- * 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)
+ /* Compaction run completes if the migrate and free scanner meet */
+ if (cc->free_pfn <= cc->migrate_pfn)
return COMPACT_COMPLETE;
/*
@@ -863,15 +815,8 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
/* Setup to move all movable pages to the end of the zone */
cc->migrate_pfn = zone->zone_start_pfn;
-
- 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);
- }
+ cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
+ cc->free_pfn &= ~(pageblock_nr_pages-1);
migrate_prep_local();
diff --git a/mm/internal.h b/mm/internal.h
index 97664be2ca3..6f6bb9ab938 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -118,14 +118,8 @@ struct compact_control {
unsigned long nr_freepages; /* Number of isolated free pages */
unsigned long nr_migratepages; /* Number of pages to migrate */
unsigned long free_pfn; /* isolate_freepages search base */
- unsigned long start_free_pfn; /* where we started the search */
unsigned long migrate_pfn; /* isolate_migratepages search base */
bool sync; /* Synchronous migration */
- bool wrapped; /* Order > 0 compactions are
- incremental, once free_pfn
- and migrate_pfn meet, we restart
- from the top of the zone;
- remember we wrapped around. */
int order; /* order a direct compactor needs */
int migratetype; /* MOVABLE, RECLAIMABLE etc */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ca002b39b9b..628968c1ccf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4490,11 +4490,6 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
zone->spanned_pages = size;
zone->present_pages = realsize;
-#if defined CONFIG_COMPACTION || defined CONFIG_CMA
- zone->compact_cached_free_pfn = zone->zone_start_pfn +
- zone->spanned_pages;
- zone->compact_cached_free_pfn &= ~(pageblock_nr_pages-1);
-#endif
#ifdef CONFIG_NUMA
zone->node = nid;
zone->min_unmapped_pages = (realsize*sysctl_min_unmapped_ratio)