Re: [PATCH 09/12] Add /proc trigger for memory compaction

[Mel Gorman]

On Fri, Feb 19, 2010 at 09:43:26AM +0900, KAMEZAWA Hiroyuki wrote:
> On Thu, 18 Feb 2010 18:02:39 +0000
> Mel Gorman <mel@xxxxxxxxx> wrote:
> 
> > This patch adds a proc file /proc/sys/vm/compact_memory. When an arbitrary
> > value is written to the file, all zones are compacted. The expected user
> > of such a trigger is a job scheduler that prepares the system before the
> > target application runs.
> > 
> > Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> > Acked-by: Rik van Riel <riel@xxxxxxxxxx>
> 
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> 
> Nitpick:
> Hmm.. Is this necessary if we have per-node trigger in sysfs ?
> 

What does !NUMA do?

> Thanks,
> -Kame
> 
> 
> > ---
> >  Documentation/sysctl/vm.txt |   11 ++++++++
> >  include/linux/compaction.h  |    5 +++
> >  kernel/sysctl.c             |   11 ++++++++
> >  mm/compaction.c             |   60 +++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 87 insertions(+), 0 deletions(-)
> > 
> > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> > index fc5790d..92b5b00 100644
> > --- a/Documentation/sysctl/vm.txt
> > +++ b/Documentation/sysctl/vm.txt
> > @@ -19,6 +19,7 @@ files can be found in mm/swap.c.
> >  Currently, these files are in /proc/sys/vm:
> >  
> >  - block_dump
> > +- compact_memory
> >  - dirty_background_bytes
> >  - dirty_background_ratio
> >  - dirty_bytes
> > @@ -64,6 +65,16 @@ information on block I/O debugging is in Documentation/laptops/laptop-mode.txt.
> >  
> >  ==============================================================
> >  
> > +compact_memory
> > +
> > +Available only when CONFIG_COMPACTION is set. When an arbitrary value
> > +is written to the file, all zones are compacted such that free memory
> > +is available in contiguous blocks where possible. This can be important
> > +for example in the allocation of huge pages although processes will also
> > +directly compact memory as required.
> > +
> > +==============================================================
> > +
> >  dirty_background_bytes
> >  
> >  Contains the amount of dirty memory at which the pdflush background writeback
> > diff --git a/include/linux/compaction.h b/include/linux/compaction.h
> > index 6201371..facaa3d 100644
> > --- a/include/linux/compaction.h
> > +++ b/include/linux/compaction.h
> > @@ -5,4 +5,9 @@
> >  #define COMPACT_INCOMPLETE	0
> >  #define COMPACT_COMPLETE	1
> >  
> > +#ifdef CONFIG_COMPACTION
> > +extern int sysctl_compaction_handler(struct ctl_table *table, int write,
> > +			void __user *buffer, size_t *length, loff_t *ppos);
> > +#endif /* CONFIG_COMPACTION */
> > +
> >  #endif /* _LINUX_COMPACTION_H */
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index 8a68b24..a02c816 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -50,6 +50,7 @@
> >  #include <linux/ftrace.h>
> >  #include <linux/slow-work.h>
> >  #include <linux/perf_event.h>
> > +#include <linux/compaction.h>
> >  
> >  #include <asm/uaccess.h>
> >  #include <asm/processor.h>
> > @@ -80,6 +81,7 @@ extern int pid_max;
> >  extern int min_free_kbytes;
> >  extern int pid_max_min, pid_max_max;
> >  extern int sysctl_drop_caches;
> > +extern int sysctl_compact_memory;
> >  extern int percpu_pagelist_fraction;
> >  extern int compat_log;
> >  extern int latencytop_enabled;
> > @@ -1109,6 +1111,15 @@ static struct ctl_table vm_table[] = {
> >  		.mode		= 0644,
> >  		.proc_handler	= drop_caches_sysctl_handler,
> >  	},
> > +#ifdef CONFIG_COMPACTION
> > +	{
> > +		.procname	= "compact_memory",
> > +		.data		= &sysctl_compact_memory,
> > +		.maxlen		= sizeof(int),
> > +		.mode		= 0200,
> > +		.proc_handler	= sysctl_compaction_handler,
> > +	},
> > +#endif /* CONFIG_COMPACTION */
> >  	{
> >  		.procname	= "min_free_kbytes",
> >  		.data		= &min_free_kbytes,
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index 14ba0ac..22f223f 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -11,6 +11,7 @@
> >  #include <linux/migrate.h>
> >  #include <linux/compaction.h>
> >  #include <linux/mm_inline.h>
> > +#include <linux/sysctl.h>
> >  #include "internal.h"
> >  
> >  /*
> > @@ -345,3 +346,62 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
> >  	return ret;
> >  }
> >  
> > +/* Compact all zones within a node */
> > +static int compact_node(int nid)
> > +{
> > +	int zoneid;
> > +	pg_data_t *pgdat;
> > +	struct zone *zone;
> > +
> > +	if (nid < 0 || nid > nr_node_ids || !node_online(nid))
> > +		return -EINVAL;
> > +	pgdat = NODE_DATA(nid);
> > +
> > +	/* Flush pending updates to the LRU lists */
> > +	lru_add_drain_all();
> > +
> > +	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
> > +		struct compact_control cc;
> > +
> > +		zone = &pgdat->node_zones[zoneid];
> > +		if (!populated_zone(zone))
> > +			continue;
> > +
> > +		cc.nr_freepages = 0;
> > +		cc.nr_migratepages = 0;
> > +		cc.zone = zone;
> > +		INIT_LIST_HEAD(&cc.freepages);
> > +		INIT_LIST_HEAD(&cc.migratepages);
> > +
> > +		compact_zone(zone, &cc);
> > +
> > +		VM_BUG_ON(!list_empty(&cc.freepages));
> > +		VM_BUG_ON(!list_empty(&cc.migratepages));
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +/* Compact all nodes in the system */
> > +static int compact_nodes(void)
> > +{
> > +	int nid;
> > +
> > +	for_each_online_node(nid)
> > +		compact_node(nid);
> > +
> > +	return COMPACT_COMPLETE;
> > +}
> > +
> > +/* The written value is actually unused, all memory is compacted */
> > +int sysctl_compact_memory;
> > +
> > +/* This is the entry point for compacting all nodes via /proc/sys/vm */
> > +int sysctl_compaction_handler(struct ctl_table *table, int write,
> > +			void __user *buffer, size_t *length, loff_t *ppos)
> > +{
> > +	if (write)
> > +		return compact_nodes();
> > +
> > +	return 0;
> > +}
> > -- 
> > 1.6.5
> > 
> > --
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> > 
> 

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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