Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753314Ab0BRSGR (ORCPT ); Thu, 18 Feb 2010 13:06:17 -0500 Received: from gir.skynet.ie ([193.1.99.77]:44713 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751425Ab0BRSCs (ORCPT ); Thu, 18 Feb 2010 13:02:48 -0500 From: Mel Gorman To: Andrea Arcangeli Cc: Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , KOSAKI Motohiro , Rik van Riel , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 07/12] Export fragmentation index via /proc/pagetypeinfo Date: Thu, 18 Feb 2010 18:02:37 +0000 Message-Id: <1266516162-14154-8-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.6.5 In-Reply-To: <1266516162-14154-1-git-send-email-mel@csn.ul.ie> References: <1266516162-14154-1-git-send-email-mel@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5914 Lines: 166 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/pagetypeinfo. Signed-off-by: Mel Gorman --- Documentation/filesystems/proc.txt | 14 ++++++- mm/vmstat.c | 81 ++++++++++++++++++++++++++++++++++++ 2 files changed, 94 insertions(+), 1 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 57869d0..24396ab 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -412,6 +412,7 @@ 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 @@ -597,7 +598,7 @@ 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 unusable_index +pagetypeinfo, unusable_index and extfrag_index. > cat /proc/pagetypeinfo Page block order: 9 @@ -648,6 +649,17 @@ value between 0 and 1. The higher the value, the more of free memory is unusable and by implication, the worse the external fragmentation is. This can be expressed as a percentage by multiplying by 100. +> 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 23f217e..fa5975c 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -551,6 +551,67 @@ static int unusable_show(struct seq_file *m, void *arg) return 0; } +/* + * 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 - ( (1000+(info->free_pages * 1000 / 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) { @@ -720,6 +781,25 @@ static const struct file_operations unusable_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 @@ -1064,6 +1144,7 @@ static int __init setup_vmstat(void) proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations); proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops); proc_create("unusable_index", S_IRUGO, NULL, &unusable_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 -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/