From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 9302862008A for ; Wed, 7 Apr 2010 22:57:14 -0400 (EDT) Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [PATCH 54 of 67] Export fragmentation index via /proc/extfrag_index Message-Id: <8e4a8a4deb5121c65e0c.1270691497@v2.random> In-Reply-To: References: Date: Thu, 08 Apr 2010 03:51:37 +0200 From: Andrea Arcangeli Sender: owner-linux-mm@kvack.org To: linux-mm@kvack.org, Andrew Morton Cc: Marcelo Tosatti , Adam Litke , Avi Kivity , Izik Eidus , Hugh Dickins , Nick Piggin , Rik van Riel , Mel Gorman , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , Arnd Bergmann , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura , Chris Mason List-ID: From: Mel Gorman 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 Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Acked-by: Rik van Riel Reviewed-by: Christoph Lameter --- diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -420,6 +420,7 @@ 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 @@ -605,7 +606,7 @@ ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in Z 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 @@ -656,6 +657,17 @@ value between 0 and 1. The higher the va 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 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -16,6 +16,7 @@ #include #include #include +#include #ifdef CONFIG_VM_EVENT_COUNTERS DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}}; @@ -554,6 +555,67 @@ static int unusable_show(struct seq_file 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 - 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) { @@ -723,6 +785,25 @@ static const struct file_operations unus .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 @@ -1071,6 +1152,7 @@ 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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