From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 722176B02B4 for ; Fri, 21 Jul 2017 10:39:27 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id c184so5255068wmd.6 for ; Fri, 21 Jul 2017 07:39:27 -0700 (PDT) Received: from mail-wr0-f195.google.com (mail-wr0-f195.google.com. [209.85.128.195]) by mx.google.com with ESMTPS id p76si4203290wrc.548.2017.07.21.07.39.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Jul 2017 07:39:25 -0700 (PDT) Received: by mail-wr0-f195.google.com with SMTP id o33so4961435wrb.1 for ; Fri, 21 Jul 2017 07:39:25 -0700 (PDT) From: Michal Hocko Subject: [PATCH 1/9] mm, page_alloc: rip out ZONELIST_ORDER_ZONE Date: Fri, 21 Jul 2017 16:39:07 +0200 Message-Id: <20170721143915.14161-2-mhocko@kernel.org> In-Reply-To: <20170721143915.14161-1-mhocko@kernel.org> References: <20170721143915.14161-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , Johannes Weiner , Vlastimil Babka , linux-mm@kvack.org, LKML , Michal Hocko From: Michal Hocko Supporting zone ordered zonelists costs us just a lot of code while the usefulness is arguable if existent at all. Mel has already made node ordering default on 64b systems. 32b systems are still using ZONELIST_ORDER_ZONE because it is considered better to fallback to a different NUMA node rather than consume precious lowmem zones. This argument is, however, weaken by the fact that the memory reclaim has been reworked to be node rather than zone oriented. This means that lowmem requests have to skip over all highmem pages on LRUs already and so zone ordering doesn't save the reclaim time much. So the only advantage of the zone ordering is under a light memory pressure when highmem requests do not ever hit into lowmem zones and the lowmem pressure doesn't need to reclaim. Considering that 32b NUMA systems are rather suboptimal already and it is generally advisable to use 64b kernel on such a HW I believe we should rather care about the code maintainability and just get rid of ZONELIST_ORDER_ZONE altogether. Keep systcl in place and warn if somebody tries to set zone ordering either from kernel command line or the sysctl. Changes since v1 - do not print Default in sysctl handler because our behavior was rather inconsistent in the past numa_zonelist_order was lowecase while zonelist_order_name was uppercase so boot time unchanged value woul print lowercase while updated value could be uppercase. Print "Node" which is the default instead - Mel - update documentation - Vlastimil Cc: linux-api@vger.kernel.org Acked-by: Mel Gorman Acked-by: Vlastimil Babka Signed-off-by: Michal Hocko --- Documentation/admin-guide/kernel-parameters.txt | 2 +- Documentation/sysctl/vm.txt | 4 +- Documentation/vm/numa | 7 +- include/linux/mmzone.h | 2 - kernel/sysctl.c | 2 - mm/page_alloc.c | 178 +++--------------------- 6 files changed, 29 insertions(+), 166 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 60530c8490ff..28f1a0f84456 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2724,7 +2724,7 @@ Allowed values are enable and disable numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. - one of ['zone', 'node', 'default'] can be specified + 'node', 'default' can be specified This can be set from sysctl after boot. See Documentation/sysctl/vm.txt for details. diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 48244c42ff52..9baf66a9ef4e 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -572,7 +572,9 @@ See Documentation/nommu-mmap.txt for more information. numa_zonelist_order -This sysctl is only for NUMA. +This sysctl is only for NUMA and it is deprecated. Anything but +Node order will fail! + 'where the memory is allocated from' is controlled by zonelists. (This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation. you may be able to read ZONE_DMA as ZONE_DMA32...) diff --git a/Documentation/vm/numa b/Documentation/vm/numa index a08f71647714..a31b85b9bb88 100644 --- a/Documentation/vm/numa +++ b/Documentation/vm/numa @@ -79,11 +79,8 @@ memory, Linux must decide whether to order the zonelists such that allocations fall back to the same zone type on a different node, or to a different zone type on the same node. This is an important consideration because some zones, such as DMA or DMA32, represent relatively scarce resources. Linux chooses -a default zonelist order based on the sizes of the various zone types relative -to the total memory of the node and the total memory of the system. The -default zonelist order may be overridden using the numa_zonelist_order kernel -boot parameter or sysctl. [see Documentation/admin-guide/kernel-parameters.rst and -Documentation/sysctl/vm.txt] +a default Node ordered zonelist. This means it tries to fallback to other zones +from the same node before using remote nodes which are ordered by NUMA distance. By default, Linux will attempt to satisfy memory allocation requests from the node to which the CPU that executes the request is assigned. Specifically, diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index fc14b8b3f6ce..b849006b20d3 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -895,8 +895,6 @@ int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int, extern int numa_zonelist_order_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); -extern char numa_zonelist_order[]; -#define NUMA_ZONELIST_ORDER_LEN 16 /* string buffer size */ #ifndef CONFIG_NEED_MULTIPLE_NODES diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 655686d546cb..0cbce40f5426 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1553,8 +1553,6 @@ static struct ctl_table vm_table[] = { #ifdef CONFIG_NUMA { .procname = "numa_zonelist_order", - .data = &numa_zonelist_order, - .maxlen = NUMA_ZONELIST_ORDER_LEN, .mode = 0644, .proc_handler = numa_zonelist_order_handler, }, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 80e4adb4c360..b839a90e24c8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4791,52 +4791,18 @@ static int build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist, return nr_zones; } - -/* - * zonelist_order: - * 0 = automatic detection of better ordering. - * 1 = order by ([node] distance, -zonetype) - * 2 = order by (-zonetype, [node] distance) - * - * If not NUMA, ZONELIST_ORDER_ZONE and ZONELIST_ORDER_NODE will create - * the same zonelist. So only NUMA can configure this param. - */ -#define ZONELIST_ORDER_DEFAULT 0 -#define ZONELIST_ORDER_NODE 1 -#define ZONELIST_ORDER_ZONE 2 - -/* zonelist order in the kernel. - * set_zonelist_order() will set this to NODE or ZONE. - */ -static int current_zonelist_order = ZONELIST_ORDER_DEFAULT; -static char zonelist_order_name[3][8] = {"Default", "Node", "Zone"}; - - #ifdef CONFIG_NUMA -/* The value user specified ....changed by config */ -static int user_zonelist_order = ZONELIST_ORDER_DEFAULT; -/* string for sysctl */ -#define NUMA_ZONELIST_ORDER_LEN 16 -char numa_zonelist_order[16] = "default"; - -/* - * interface for configure zonelist ordering. - * command line option "numa_zonelist_order" - * = "[dD]efault - default, automatic configuration. - * = "[nN]ode - order by node locality, then by zone within node - * = "[zZ]one - order by zone, then by locality within zone - */ static int __parse_numa_zonelist_order(char *s) { - if (*s == 'd' || *s == 'D') { - user_zonelist_order = ZONELIST_ORDER_DEFAULT; - } else if (*s == 'n' || *s == 'N') { - user_zonelist_order = ZONELIST_ORDER_NODE; - } else if (*s == 'z' || *s == 'Z') { - user_zonelist_order = ZONELIST_ORDER_ZONE; - } else { - pr_warn("Ignoring invalid numa_zonelist_order value: %s\n", s); + /* + * We used to support different zonlists modes but they turned + * out to be just not useful. Let's keep the warning in place + * if somebody still use the cmd line parameter so that we do + * not fail it silently + */ + if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) { + pr_warn("Ignoring unsupported numa_zonelist_order value: %s\n", s); return -EINVAL; } return 0; @@ -4844,16 +4810,10 @@ static int __parse_numa_zonelist_order(char *s) static __init int setup_numa_zonelist_order(char *s) { - int ret; - if (!s) return 0; - ret = __parse_numa_zonelist_order(s); - if (ret == 0) - strlcpy(numa_zonelist_order, s, NUMA_ZONELIST_ORDER_LEN); - - return ret; + return __parse_numa_zonelist_order(s); } early_param("numa_zonelist_order", setup_numa_zonelist_order); @@ -4864,40 +4824,22 @@ int numa_zonelist_order_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) { - char saved_string[NUMA_ZONELIST_ORDER_LEN]; + char *str; int ret; - static DEFINE_MUTEX(zl_order_mutex); - mutex_lock(&zl_order_mutex); - if (write) { - if (strlen((char *)table->data) >= NUMA_ZONELIST_ORDER_LEN) { - ret = -EINVAL; - goto out; - } - strcpy(saved_string, (char *)table->data); + if (!write) { + int len = sizeof("Node"); + if (copy_to_user(buffer, "Node", len)) + return -EFAULT; + return len; } - ret = proc_dostring(table, write, buffer, length, ppos); - if (ret) - goto out; - if (write) { - int oldval = user_zonelist_order; - ret = __parse_numa_zonelist_order((char *)table->data); - if (ret) { - /* - * bogus value. restore saved string - */ - strncpy((char *)table->data, saved_string, - NUMA_ZONELIST_ORDER_LEN); - user_zonelist_order = oldval; - } else if (oldval != user_zonelist_order) { - mutex_lock(&zonelists_mutex); - build_all_zonelists(NULL, NULL); - mutex_unlock(&zonelists_mutex); - } - } -out: - mutex_unlock(&zl_order_mutex); + str = memdup_user_nul(buffer, 16); + if (IS_ERR(str)) + return PTR_ERR(str); + + ret = __parse_numa_zonelist_order(str); + kfree(str); return ret; } @@ -5006,70 +4948,12 @@ static void build_thisnode_zonelists(pg_data_t *pgdat) */ static int node_order[MAX_NUMNODES]; -static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes) -{ - int pos, j, node; - int zone_type; /* needs to be signed */ - struct zone *z; - struct zonelist *zonelist; - - zonelist = &pgdat->node_zonelists[ZONELIST_FALLBACK]; - pos = 0; - for (zone_type = MAX_NR_ZONES - 1; zone_type >= 0; zone_type--) { - for (j = 0; j < nr_nodes; j++) { - node = node_order[j]; - z = &NODE_DATA(node)->node_zones[zone_type]; - if (managed_zone(z)) { - zoneref_set_zone(z, - &zonelist->_zonerefs[pos++]); - check_highest_zone(zone_type); - } - } - } - zonelist->_zonerefs[pos].zone = NULL; - zonelist->_zonerefs[pos].zone_idx = 0; -} - -#if defined(CONFIG_64BIT) -/* - * Devices that require DMA32/DMA are relatively rare and do not justify a - * penalty to every machine in case the specialised case applies. Default - * to Node-ordering on 64-bit NUMA machines - */ -static int default_zonelist_order(void) -{ - return ZONELIST_ORDER_NODE; -} -#else -/* - * On 32-bit, the Normal zone needs to be preserved for allocations accessible - * by the kernel. If processes running on node 0 deplete the low memory zone - * then reclaim will occur more frequency increasing stalls and potentially - * be easier to OOM if a large percentage of the zone is under writeback or - * dirty. The problem is significantly worse if CONFIG_HIGHPTE is not set. - * Hence, default to zone ordering on 32-bit. - */ -static int default_zonelist_order(void) -{ - return ZONELIST_ORDER_ZONE; -} -#endif /* CONFIG_64BIT */ - -static void set_zonelist_order(void) -{ - if (user_zonelist_order == ZONELIST_ORDER_DEFAULT) - current_zonelist_order = default_zonelist_order(); - else - current_zonelist_order = user_zonelist_order; -} - static void build_zonelists(pg_data_t *pgdat) { int i, node, load; nodemask_t used_mask; int local_node, prev_node; struct zonelist *zonelist; - unsigned int order = current_zonelist_order; /* initialize zonelists */ for (i = 0; i < MAX_ZONELISTS; i++) { @@ -5099,15 +4983,7 @@ static void build_zonelists(pg_data_t *pgdat) prev_node = node; load--; - if (order == ZONELIST_ORDER_NODE) - build_zonelists_in_node_order(pgdat, node); - else - node_order[i++] = node; /* remember order */ - } - - if (order == ZONELIST_ORDER_ZONE) { - /* calculate node order -- i.e., DMA last! */ - build_zonelists_in_zone_order(pgdat, i); + build_zonelists_in_node_order(pgdat, node); } build_thisnode_zonelists(pgdat); @@ -5135,11 +5011,6 @@ static void setup_min_unmapped_ratio(void); static void setup_min_slab_ratio(void); #else /* CONFIG_NUMA */ -static void set_zonelist_order(void) -{ - current_zonelist_order = ZONELIST_ORDER_ZONE; -} - static void build_zonelists(pg_data_t *pgdat) { int node, local_node; @@ -5279,8 +5150,6 @@ build_all_zonelists_init(void) */ void __ref build_all_zonelists(pg_data_t *pgdat, struct zone *zone) { - set_zonelist_order(); - if (system_state == SYSTEM_BOOTING) { build_all_zonelists_init(); } else { @@ -5306,9 +5175,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat, struct zone *zone) else page_group_by_mobility_disabled = 0; - pr_info("Built %i zonelists in %s order, mobility grouping %s. Total pages: %ld\n", + pr_info("Built %i zonelists, mobility grouping %s. Total pages: %ld\n", nr_online_nodes, - zonelist_order_name[current_zonelist_order], page_group_by_mobility_disabled ? "off" : "on", vm_total_pages); #ifdef CONFIG_NUMA -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org