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revert "mm: have order > 0 compaction start off where it left"

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This reverts commit 7db8889ab0 ("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>
This commit is contained in:
Mel Gorman 2012-10-08 16:32:40 -07:00 committed by Linus Torvalds
parent f40d1e42bb
commit 753341a4b8
4 changed files with 5 additions and 75 deletions
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4
include/linux/mmzone.h
View File

@ -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;

65
mm/compaction.c
View File

@ -537,20 +537,6 @@ 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();

6
mm/internal.h
View File

@ -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 */

5
mm/page_alloc.c
View File

@ -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)