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Commit 23b9da55 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: vmscan: remove reclaim_mode_t 



There is little motiviation for reclaim_mode_t once RECLAIM_MODE_[A]SYNC
and lumpy reclaim have been removed.  This patch gets rid of
reclaim_mode_t as well and improves the documentation about what
reclaim/compaction is and when it is triggered.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 41ac1999

include/trace/events/vmscan.h

+2 −2
Original line number Diff line number Diff line
@@ -25,12 +25,12 @@ 
		{RECLAIM_WB_ASYNC,	"RECLAIM_WB_ASYNC"}	\

		) : "RECLAIM_WB_NONE"



#define trace_reclaim_flags(page, sync) ( \

#define trace_reclaim_flags(page) ( \

	(page_is_file_cache(page) ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \

	(RECLAIM_WB_ASYNC) \

	)



#define trace_shrink_flags(file, sync) \

#define trace_shrink_flags(file) \

	( \

		(file ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \

		(RECLAIM_WB_ASYNC) \

mm/vmscan.c

+22 −50
Original line number Diff line number Diff line
@@ -53,16 +53,6 @@ 
#define CREATE_TRACE_POINTS

#include <trace/events/vmscan.h>



/*

 * reclaim_mode determines how the inactive list is shrunk

 * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages

 * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of

 *			order-0 pages and then compact the zone

 */

typedef unsigned __bitwise__ reclaim_mode_t;

#define RECLAIM_MODE_SINGLE		((__force reclaim_mode_t)0x01u)

#define RECLAIM_MODE_COMPACTION		((__force reclaim_mode_t)0x10u)



struct scan_control {

	/* Incremented by the number of inactive pages that were scanned */

	unsigned long nr_scanned;
@@ -88,12 +78,6 @@ struct scan_control { 


	int order;



	/*

	 * Intend to reclaim enough continuous memory rather than reclaim

	 * enough amount of memory. i.e, mode for high order allocation.

	 */

	reclaim_mode_t reclaim_mode;



	/*

	 * The memory cgroup that hit its limit and as a result is the

	 * primary target of this reclaim invocation.
@@ -356,25 +340,6 @@ unsigned long shrink_slab(struct shrink_control *shrink, 
	return ret;

}



static void set_reclaim_mode(int priority, struct scan_control *sc)

{

	/*

	 * Restrict reclaim/compaction to costly allocations or when

	 * under memory pressure

	 */

	if (COMPACTION_BUILD && sc->order &&

			(sc->order > PAGE_ALLOC_COSTLY_ORDER ||

			 priority < DEF_PRIORITY - 2))

		sc->reclaim_mode = RECLAIM_MODE_COMPACTION;

	else

		sc->reclaim_mode = RECLAIM_MODE_SINGLE;

}



static void reset_reclaim_mode(struct scan_control *sc)

{

	sc->reclaim_mode = RECLAIM_MODE_SINGLE;

}



static inline int is_page_cache_freeable(struct page *page)

{

	/*
@@ -497,8 +462,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, 
			/* synchronous write or broken a_ops? */

			ClearPageReclaim(page);

		}

		trace_mm_vmscan_writepage(page,

			trace_reclaim_flags(page, sc->reclaim_mode));

		trace_mm_vmscan_writepage(page, trace_reclaim_flags(page));

		inc_zone_page_state(page, NR_VMSCAN_WRITE);

		return PAGE_SUCCESS;

	}
@@ -953,7 +917,6 @@ static unsigned long shrink_page_list(struct list_head *page_list, 
			try_to_free_swap(page);

		unlock_page(page);

		putback_lru_page(page);

		reset_reclaim_mode(sc);

		continue;



activate_locked:
@@ -1348,8 +1311,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz, 
			return SWAP_CLUSTER_MAX;

	}



	set_reclaim_mode(priority, sc);



	lru_add_drain();



	if (!sc->may_unmap)
@@ -1433,7 +1394,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz, 
		zone_idx(zone),

		nr_scanned, nr_reclaimed,

		priority,

		trace_shrink_flags(file, sc->reclaim_mode));

		trace_shrink_flags(file));

	return nr_reclaimed;

}
@@ -1512,8 +1473,6 @@ static void shrink_active_list(unsigned long nr_to_scan, 


	lru_add_drain();



	reset_reclaim_mode(sc);



	if (!sc->may_unmap)

		isolate_mode |= ISOLATE_UNMAPPED;

	if (!sc->may_writepage)
@@ -1826,23 +1785,35 @@ static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc, 
	}

}



/* Use reclaim/compaction for costly allocs or under memory pressure */

static bool in_reclaim_compaction(int priority, struct scan_control *sc)

{

	if (COMPACTION_BUILD && sc->order &&

			(sc->order > PAGE_ALLOC_COSTLY_ORDER ||

			 priority < DEF_PRIORITY - 2))

		return true;



	return false;

}



/*

 * Reclaim/compaction depends on a number of pages being freed. To avoid

 * disruption to the system, a small number of order-0 pages continue to be

 * rotated and reclaimed in the normal fashion. However, by the time we get

 * back to the allocator and call try_to_compact_zone(), we ensure that

 * there are enough free pages for it to be likely successful

 * Reclaim/compaction is used for high-order allocation requests. It reclaims

 * order-0 pages before compacting the zone. should_continue_reclaim() returns

 * true if more pages should be reclaimed such that when the page allocator

 * calls try_to_compact_zone() that it will have enough free pages to succeed.

 * It will give up earlier than that if there is difficulty reclaiming pages.

 */

static inline bool should_continue_reclaim(struct mem_cgroup_zone *mz,

					unsigned long nr_reclaimed,

					unsigned long nr_scanned,

					int priority,

					struct scan_control *sc)

{

	unsigned long pages_for_compaction;

	unsigned long inactive_lru_pages;



	/* If not in reclaim/compaction mode, stop */

	if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))

	if (!in_reclaim_compaction(priority, sc))

		return false;



	/* Consider stopping depending on scan and reclaim activity */
@@ -1944,7 +1915,8 @@ static void shrink_mem_cgroup_zone(int priority, struct mem_cgroup_zone *mz, 


	/* reclaim/compaction might need reclaim to continue */

	if (should_continue_reclaim(mz, nr_reclaimed,

					sc->nr_scanned - nr_scanned, sc))

					sc->nr_scanned - nr_scanned,

					priority, sc))

		goto restart;



	throttle_vm_writeout(sc->gfp_mask);