From: Mel Gorman Date: Mon, 8 Oct 2012 23:32:40 +0000 (-0700) Subject: revert "mm: have order > 0 compaction start off where it left" X-Git-Tag: firefly_0821_release~3680^2~1857^2~60 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=753341a4b85ff337487b9959c71c529f522004f4;p=firefly-linux-kernel-4.4.55.git 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 Acked-by: Rik van Riel Cc: Richard Davies Cc: Shaohua Li Cc: Avi Kivity Acked-by: Rafael Aquini Acked-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 85ac67aa5770..16a4cc2950a0 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 bdf6e13045ea..db76361a3117 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -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(); diff --git a/mm/internal.h b/mm/internal.h index 97664be2ca37..6f6bb9ab9386 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 ca002b39b9b4..628968c1ccf4 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)