From: Mel Gorman <mel@csn.ul.ie>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Christoph Lameter <cl@linux-foundation.org>,
Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>,
David Rientjes <rientjes@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mel@csn.ul.ie>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 07/14] mm: Export fragmentation index via debugfs
Date: Tue, 20 Apr 2010 22:01:09 +0100 [thread overview]
Message-ID: <1271797276-31358-8-git-send-email-mel@csn.ul.ie> (raw)
In-Reply-To: <1271797276-31358-1-git-send-email-mel@csn.ul.ie>
The fragmentation 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.
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-zo
basis via /sys/kernel/debug/extfrag/extfrag_index
> cat /sys/kernel/debug/extfrag/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
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
---
mm/vmstat.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index d3e0fa1..23a5899 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -16,6 +16,7 @@
#include <linux/cpu.h>
#include <linux/vmstat.h>
#include <linux/sched.h>
+#include <linux/math64.h>
#ifdef CONFIG_VM_EVENT_COUNTERS
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
@@ -420,6 +421,33 @@ static void fill_contig_page_info(struct zone *zone,
(order - suitable_order);
}
}
+
+/*
+ * A fragmentation index only makes sense if an allocation of a requested
+ * size would fail. If that is true, the fragmentation index indicates
+ * whether external fragmentation or a lack of memory was the problem.
+ * The value can be used to determine if page reclaim or compaction
+ * should be used
+ */
+int fragmentation_index(unsigned int order, struct contig_page_info *info)
+{
+ unsigned long requested = 1UL << order;
+
+ if (!info->free_blocks_total)
+ return 0;
+
+ /* Fragmentation index only makes sense when a request would fail */
+ if (info->free_blocks_suitable)
+ return -1000;
+
+ /*
+ * Index is between 0 and 1 so return within 3 decimal places
+ *
+ * 0 => allocation would fail due to lack of memory
+ * 1 => allocation would fail due to fragmentation
+ */
+ return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
+}
#endif
#if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
@@ -1087,6 +1115,58 @@ 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);
@@ -1097,6 +1177,10 @@ 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;
}
--
1.6.5
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next prev parent reply other threads:[~2010-04-20 21:01 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-20 21:01 [PATCH 0/14] Memory Compaction v8 Mel Gorman
2010-04-20 21:01 ` [PATCH 01/14] mm,migration: Take a reference to the anon_vma before migrating Mel Gorman
2010-04-21 2:49 ` KAMEZAWA Hiroyuki
2010-04-20 21:01 ` [PATCH 02/14] mm,migration: Share the anon_vma ref counts between KSM and page migration Mel Gorman
2010-04-20 21:01 ` [PATCH 03/14] mm,migration: Do not try to migrate unmapped anonymous pages Mel Gorman
2010-04-20 21:01 ` [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages Mel Gorman
2010-04-21 14:30 ` Christoph Lameter
2010-04-21 15:00 ` Mel Gorman
2010-04-21 15:05 ` Christoph Lameter
2010-04-21 15:14 ` Mel Gorman
2010-04-21 15:31 ` Christoph Lameter
2010-04-21 15:34 ` Mel Gorman
2010-04-21 15:46 ` Christoph Lameter
2010-04-22 9:28 ` Mel Gorman
2010-04-22 9:46 ` KAMEZAWA Hiroyuki
2010-04-22 10:13 ` Minchan Kim
2010-04-22 10:31 ` KAMEZAWA Hiroyuki
2010-04-22 10:51 ` KAMEZAWA Hiroyuki
2010-04-22 14:14 ` Mel Gorman
2010-04-22 14:18 ` Minchan Kim
2010-04-22 15:40 ` Mel Gorman
2010-04-22 16:13 ` Mel Gorman
2010-04-22 19:29 ` Mel Gorman
2010-04-22 19:40 ` Christoph Lameter
2010-04-22 23:52 ` KAMEZAWA Hiroyuki
2010-04-23 9:03 ` Mel Gorman
2010-04-22 14:23 ` Minchan Kim
2010-04-22 14:40 ` Minchan Kim
2010-04-22 15:44 ` Mel Gorman
2010-04-23 18:31 ` Andrea Arcangeli
2010-04-23 19:23 ` Mel Gorman
2010-04-23 19:39 ` Andrea Arcangeli
2010-04-23 21:35 ` Andrea Arcangeli
2010-04-24 10:52 ` Mel Gorman
2010-04-24 11:13 ` Andrea Arcangeli
2010-04-24 11:59 ` Mel Gorman
2010-04-24 14:30 ` Andrea Arcangeli
2010-04-26 21:54 ` Rik van Riel
2010-04-26 22:11 ` Mel Gorman
2010-04-26 22:26 ` Andrea Arcangeli
2010-04-25 14:41 ` Andrea Arcangeli
2010-04-27 9:40 ` Mel Gorman
2010-04-27 10:41 ` KAMEZAWA Hiroyuki
2010-04-27 11:12 ` Mel Gorman
2010-04-27 15:42 ` Andrea Arcangeli
2010-04-24 10:50 ` Mel Gorman
2010-04-22 15:14 ` Christoph Lameter
2010-04-23 3:39 ` Paul E. McKenney
2010-04-23 4:55 ` Minchan Kim
2010-04-21 23:59 ` KAMEZAWA Hiroyuki
2010-04-22 0:11 ` Minchan Kim
2010-04-20 21:01 ` [PATCH 05/14] mm: Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove Mel Gorman
2010-04-20 21:01 ` [PATCH 06/14] mm: Export unusable free space index via debugfs Mel Gorman
2010-04-20 21:01 ` Mel Gorman [this message]
2010-04-20 21:01 ` [PATCH 08/14] mm: Move definition for LRU isolation modes to a header Mel Gorman
2010-04-20 21:01 ` [PATCH 09/14] mm,compaction: Memory compaction core Mel Gorman
2010-04-20 21:01 ` [PATCH 10/14] mm,compaction: Add /proc trigger for memory compaction Mel Gorman
2010-04-20 21:01 ` [PATCH 11/14] mm,compaction: Add /sys trigger for per-node " Mel Gorman
2010-04-20 21:01 ` [PATCH 12/14] mm,compaction: Direct compact when a high-order allocation fails Mel Gorman
2010-05-05 12:19 ` [PATCH] fix count_vm_event preempt in memory compaction direct reclaim Andrea Arcangeli
2010-05-05 12:51 ` Mel Gorman
2010-05-05 13:11 ` Andrea Arcangeli
2010-05-05 13:55 ` Mel Gorman
2010-05-05 14:48 ` Andrea Arcangeli
2010-05-05 15:14 ` Mel Gorman
2010-05-05 15:25 ` Andrea Arcangeli
2010-05-05 15:32 ` Mel Gorman
2010-04-20 21:01 ` [PATCH 13/14] mm,compaction: Add a tunable that decides when memory should be compacted and when it should be reclaimed Mel Gorman
2010-04-20 21:01 ` [PATCH 14/14] mm,compaction: Defer compaction using an exponential backoff when compaction fails Mel Gorman
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