Commit 34aa1330 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

[PATCH] zoned vm counters: zone_reclaim: remove /proc/sys/vm/zone_reclaim_interval 



The zone_reclaim_interval was necessary because we were not able to determine
how many unmapped pages exist in a zone.  Therefore we had to scan in
intervals to figure out if any pages were unmapped.

With the zoned counters and NR_ANON_PAGES we now know the number of pagecache
pages and the number of mapped pages in a zone.  So we can simply skip the
reclaim if there is an insufficient number of unmapped pages.  We use
SWAP_CLUSTER_MAX as the boundary.

Drop all support for /proc/sys/vm/zone_reclaim_interval.

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f3dbd344

Documentation/sysctl/vm.txt

+0 −13
Original line number Diff line number Diff line
@@ -28,7 +28,6 @@ Currently, these files are in /proc/sys/vm: 
- block_dump

- drop-caches

- zone_reclaim_mode

- zone_reclaim_interval

- panic_on_oom



==============================================================
@@ -167,18 +166,6 @@ use of files and builds up large slab caches. However, the slab 
shrink operation is global, may take a long time and free slabs

in all nodes of the system.



================================================================



zone_reclaim_interval:



The time allowed for off node allocations after zone reclaim

has failed to reclaim enough pages to allow a local allocation.



Time is set in seconds and set by default to 30 seconds.



Reduce the interval if undesired off node allocations occur. However, too

frequent scans will have a negative impact onoff node allocation performance.



=============================================================



panic_on_oom

include/linux/mmzone.h

+0 −6
Original line number Diff line number Diff line
@@ -178,12 +178,6 @@ struct zone { 


	/* Zone statistics */

	atomic_long_t		vm_stat[NR_VM_ZONE_STAT_ITEMS];

	/*

	 * timestamp (in jiffies) of the last zone reclaim that did not

	 * result in freeing of pages. This is used to avoid repeated scans

	 * if all memory in the zone is in use.

	 */

	unsigned long		last_unsuccessful_zone_reclaim;



	/*

	 * prev_priority holds the scanning priority for this zone.  It is

include/linux/swap.h

+0 −1
Original line number Diff line number Diff line
@@ -189,7 +189,6 @@ extern long vm_total_pages; 


#ifdef CONFIG_NUMA

extern int zone_reclaim_mode;

extern int zone_reclaim_interval;

extern int zone_reclaim(struct zone *, gfp_t, unsigned int);

#else

#define zone_reclaim_mode 0

kernel/sysctl.c

+0 −9
Original line number Diff line number Diff line
@@ -933,15 +933,6 @@ static ctl_table vm_table[] = { 
		.strategy	= &sysctl_intvec,

		.extra1		= &zero,

	},

	{

		.ctl_name	= VM_ZONE_RECLAIM_INTERVAL,

		.procname	= "zone_reclaim_interval",

		.data		= &zone_reclaim_interval,

		.maxlen		= sizeof(zone_reclaim_interval),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec_jiffies,

		.strategy	= &sysctl_jiffies,

	},

#endif

#ifdef CONFIG_X86_32

	{

mm/vmscan.c

+10 −21
Original line number Diff line number Diff line
@@ -1517,11 +1517,6 @@ int zone_reclaim_mode __read_mostly; 
#define RECLAIM_SWAP (1<<2)	/* Swap pages out during reclaim */

#define RECLAIM_SLAB (1<<3)	/* Do a global slab shrink if the zone is out of memory */



/*

 * Mininum time between zone reclaim scans

 */

int zone_reclaim_interval __read_mostly = 30*HZ;



/*

 * Priority for ZONE_RECLAIM. This determines the fraction of pages

 * of a node considered for each zone_reclaim. 4 scans 1/16th of
@@ -1587,16 +1582,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) 


	p->reclaim_state = NULL;

	current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);



	if (nr_reclaimed == 0) {

		/*

		 * We were unable to reclaim enough pages to stay on node.  We

		 * now allow off node accesses for a certain time period before

		 * trying again to reclaim pages from the local zone.

		 */

		zone->last_unsuccessful_zone_reclaim = jiffies;

	}



	return nr_reclaimed >= nr_pages;

}
@@ -1606,13 +1591,17 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) 
	int node_id;



	/*

	 * Do not reclaim if there was a recent unsuccessful attempt at zone

	 * reclaim.  In that case we let allocations go off node for the

	 * zone_reclaim_interval.  Otherwise we would scan for each off-node

	 * page allocation.

	 * Do not reclaim if there are not enough reclaimable pages in this

	 * zone that would satify this allocations.

	 *

	 * All unmapped pagecache pages are reclaimable.

	 *

	 * Both counters may be temporarily off a bit so we use

	 * SWAP_CLUSTER_MAX as the boundary. It may also be good to

	 * leave a few frequently used unmapped pagecache pages around.

	 */

	if (time_before(jiffies,

		zone->last_unsuccessful_zone_reclaim + zone_reclaim_interval))

	if (zone_page_state(zone, NR_FILE_PAGES) -

		zone_page_state(zone, NR_FILE_MAPPED) < SWAP_CLUSTER_MAX)

			return 0;



	/*

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