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Date: Tue, 13 Apr 2010 13:43:15 +0100
From: Mel Gorman <mel@....ul.ie>
To: Andrew Morton <akpm@...ux-foundation.org>
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>,
Minchan Kim <minchan.kim@...il.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.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 06/14] Export fragmentation index via
/proc/extfrag_index
On Tue, Apr 06, 2010 at 05:05:42PM -0700, Andrew Morton wrote:
> On Fri, 2 Apr 2010 17:02:40 +0100
> > Fragmentation index is a value that makes sense when an allocation of a
> > given size would fail. The index indicates whether an allocation failure is
> > due to a lack of memory (values towards 0) or due to external fragmentation
> > (value towards 1). For the most part, the huge page size will be the size
> > of interest but not necessarily so it is exported on a per-order and per-zone
> > basis via /proc/extfrag_index
>
> (/proc/sys/vm?)
>
> Like unusable_index, this seems awfully specialised. Perhaps we could
> hide it under CONFIG_MEL, or even put it in debugfs with the intention
> of removing it in 6 or 12 months time.
> <SNIP>
==== CUT HERE ====
mm,compaction: Move extfrag_index to debugfs
extfrag_index can be worked out from userspace but for debugging and
tuning compaction, it'd be best for all users to have the same
information. This patch moves extfrag_index to debugfs where it is both
easier to configure out and remove at some future date.
This is a fix to the patch "Export fragmentation index via
/proc/extfrag_index". When merged, it'll collide with the patch "Direct
compact when a high-order allocation fails" but the resolution is
relatively straight forward - preserve the fragmentation_index functions
and delete the proc-related functions as they are now at the bottom of
the file under ifdef CONFIG_DEBUG_FS.
Signed-off-by: Mel Gorman <mel@....ul.ie>
---
Documentation/filesystems/proc.txt | 14 +----
mm/vmstat.c | 110 ++++++++++++++++++------------------
2 files changed, 57 insertions(+), 67 deletions(-)
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 66ebc11..74d2605 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -422,7 +422,6 @@ Table 1-5: Kernel info in /proc
filesystems Supported filesystems
driver Various drivers grouped here, currently rtc (2.4)
execdomains Execdomains, related to security (2.4)
- extfrag_index Additional page allocator information (see text) (2.5)
fb Frame Buffer devices (2.4)
fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
@@ -611,7 +610,7 @@ ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
available in ZONE_NORMAL, etc...
More information relevant to external fragmentation can be found in
-pagetypeinfo and extfrag_index.
+pagetypeinfo.
> cat /proc/pagetypeinfo
Page block order: 9
@@ -652,17 +651,6 @@ unless memory has been mlock()'d. Some of the Reclaimable blocks should
also be allocatable although a lot of filesystem metadata may have to be
reclaimed to achieve this.
-> cat /proc/extfrag_index
-Node 0, zone DMA -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.00
-Node 0, zone Normal -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 0.954
-
-The external fragmentation index, is only meaningful if an allocation
-would fail and indicates what the failure is due to. A value of -1 such as
-in many of the examples above states that the allocation would succeed.
-If it would fail, the value is between 0 and 1. A value tending towards
-0 implies the allocation failed due to a lack of memory. A value tending
-towards 1 implies it failed due to external fragmentation.
-
..............................................................................
meminfo:
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 582dc77..f70da05 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -522,40 +522,6 @@ int fragmentation_index(unsigned int order, struct contig_page_info *info)
return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
}
-
-static void extfrag_show_print(struct seq_file *m,
- pg_data_t *pgdat, struct zone *zone)
-{
- unsigned int order;
- int index;
-
- /* Alloc on stack as interrupts are disabled for zone walk */
- struct contig_page_info info;
-
- seq_printf(m, "Node %d, zone %8s ",
- pgdat->node_id,
- zone->name);
- for (order = 0; order < MAX_ORDER; ++order) {
- fill_contig_page_info(zone, order, &info);
- index = fragmentation_index(order, &info);
- seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
- }
-
- seq_putc(m, '\n');
-}
-
-/*
- * Display fragmentation index for orders that allocations would fail for
- */
-static int extfrag_show(struct seq_file *m, void *arg)
-{
- pg_data_t *pgdat = (pg_data_t *)arg;
-
- walk_zones_in_node(m, pgdat, extfrag_show_print);
-
- return 0;
-}
-
static void pagetypeinfo_showfree_print(struct seq_file *m,
pg_data_t *pgdat, struct zone *zone)
{
@@ -706,25 +672,6 @@ static const struct file_operations pagetypeinfo_file_ops = {
.release = seq_release,
};
-static const struct seq_operations extfrag_op = {
- .start = frag_start,
- .next = frag_next,
- .stop = frag_stop,
- .show = extfrag_show,
-};
-
-static int extfrag_open(struct inode *inode, struct file *file)
-{
- return seq_open(file, &extfrag_op);
-}
-
-static const struct file_operations extfrag_file_ops = {
- .open = extfrag_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = seq_release,
-};
-
#ifdef CONFIG_ZONE_DMA
#define TEXT_FOR_DMA(xx) xx "_dma",
#else
@@ -1069,7 +1016,6 @@ static int __init setup_vmstat(void)
#ifdef CONFIG_PROC_FS
proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
- proc_create("extfrag_index", S_IRUGO, NULL, &extfrag_file_ops);
proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
#endif
@@ -1165,6 +1111,58 @@ static const struct file_operations unusable_file_ops = {
.release = seq_release,
};
+static void extfrag_show_print(struct seq_file *m,
+ pg_data_t *pgdat, struct zone *zone)
+{
+ unsigned int order;
+ int index;
+
+ /* Alloc on stack as interrupts are disabled for zone walk */
+ struct contig_page_info info;
+
+ seq_printf(m, "Node %d, zone %8s ",
+ pgdat->node_id,
+ zone->name);
+ for (order = 0; order < MAX_ORDER; ++order) {
+ fill_contig_page_info(zone, order, &info);
+ index = fragmentation_index(order, &info);
+ seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+ }
+
+ seq_putc(m, '\n');
+}
+
+/*
+ * Display fragmentation index for orders that allocations would fail for
+ */
+static int extfrag_show(struct seq_file *m, void *arg)
+{
+ pg_data_t *pgdat = (pg_data_t *)arg;
+
+ walk_zones_in_node(m, pgdat, extfrag_show_print);
+
+ return 0;
+}
+
+static const struct seq_operations extfrag_op = {
+ .start = frag_start,
+ .next = frag_next,
+ .stop = frag_stop,
+ .show = extfrag_show,
+};
+
+static int extfrag_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &extfrag_op);
+}
+
+static const struct file_operations extfrag_file_ops = {
+ .open = extfrag_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
static int __init extfrag_debug_init(void)
{
extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
@@ -1175,6 +1173,10 @@ static int __init extfrag_debug_init(void)
extfrag_debug_root, NULL, &unusable_file_ops))
return -ENOMEM;
+ if (!debugfs_create_file("extfrag_index", 0444,
+ extfrag_debug_root, NULL, &extfrag_file_ops))
+ return -ENOMEM;
+
return 0;
}
--
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