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Message-Id: <20100219094326.e725f8e8.kamezawa.hiroyu@jp.fujitsu.com>
Date: Fri, 19 Feb 2010 09:43:26 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Mel Gorman <mel@....ul.ie>
Cc: Andrea Arcangeli <aarcange@...hat.com>,
Christoph Lameter <cl@...ux-foundation.org>,
Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>,
David Rientjes <rientjes@...gle.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCH 09/12] Add /proc trigger for memory compaction
On Thu, 18 Feb 2010 18:02:39 +0000
Mel Gorman <mel@....ul.ie> 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@....ul.ie>
> Acked-by: Rik van Riel <riel@...hat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Nitpick:
Hmm.. Is this necessary if we have per-node trigger in sysfs ?
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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