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    Subject[PATCH] change global zonelist order v4 [1/2] change zonelist ordering.

    Make zonelist creation policy selectable from sysctl v4.
    Automatic configuration itself is provided by the next patch.

    [Description]
    Assume 2 node NUMA, only node(0) has ZONE_DMA.
    (ia64's ZONE_DMA is below 4GB...x86_64's ZONE_DMA32)

    In this case, current default (node0's) zonelist order is

    Node(0)'s NORMAL -> Node(0)'s DMA -> Node(1)"s NORMAL.

    This means Node(0)'s DMA will be used before Node(1)'s NORMAL.

    This patch changes *default* zone order to

    Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.

    But, if Node(0)'s memory is too small (near or below 4G), Node(0)'s process has
    to allocate its memory from Node(1) even if there are free memory in Node(0).
    Some applications/uses will dislike this.
    This patch adds a knob to change zonelist ordering.

    [What this patch adds]

    command:
    %echo N > /proc/sys/vm/numa_zonelist_order

    Will rebuild zonelist in following order(old style, NODE order).

    Node(0)'s NORMAL -> Node(0)'s DMA -> Node(0)'s NORMAL.

    means put more priority on locality.

    command:
    %echo Z > /proc/sys/vm/numa_zonelist_order

    Will rebuild zonelist in following order(new style, ZONE order)

    Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.

    means put more priority on zone_type.

    And you can specify this option as boot param.

    Because autoconfig function does nothing. Default is "Node" order.

    Tested on ia64 2-Node NUMA. works well.

    Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

    ---
    Documentation/kernel-parameters.txt | 10 +
    Documentation/sysctl/vm.txt | 32 ++++++
    include/linux/mmzone.h | 5
    kernel/sysctl.c | 9 +
    mm/page_alloc.c | 185 ++++++++++++++++++++++++++++++++----
    5 files changed, 225 insertions(+), 16 deletions(-)

    Index: linux-2.6.21-rc7-mm2/kernel/sysctl.c
    ===================================================================
    --- linux-2.6.21-rc7-mm2.orig/kernel/sysctl.c
    +++ linux-2.6.21-rc7-mm2/kernel/sysctl.c
    @@ -893,6 +893,15 @@ static ctl_table vm_table[] = {
    .extra1 = &zero,
    .extra2 = &one_hundred,
    },
    + {
    + .ctl_name = CTL_UNNUMBERED,
    + .procname = "numa_zonelist_order",
    + .data = &numa_zonelist_order,
    + .maxlen = NUMA_ZONELIST_ORDER_LEN,
    + .mode = 0644,
    + .proc_handler = &numa_zonelist_order_handler,
    + .strategy = &sysctl_string,
    + },
    #endif
    #if defined(CONFIG_X86_32) || \
    (defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
    Index: linux-2.6.21-rc7-mm2/mm/page_alloc.c
    ===================================================================
    --- linux-2.6.21-rc7-mm2.orig/mm/page_alloc.c
    +++ linux-2.6.21-rc7-mm2/mm/page_alloc.c
    @@ -2024,7 +2024,8 @@ void show_free_areas(void)
    * Add all populated zones of a node to the zonelist.
    */
    static int __meminit build_zonelists_node(pg_data_t *pgdat,
    - struct zonelist *zonelist, int nr_zones, enum zone_type zone_type)
    + struct zonelist *zonelist, int nr_zones,
    + enum zone_type zone_type)
    {
    struct zone *zone;

    @@ -2045,7 +2046,7 @@ static int __meminit build_zonelists_nod

    #ifdef CONFIG_NUMA
    #define MAX_NODE_LOAD (num_online_nodes())
    -static int __meminitdata node_load[MAX_NUMNODES];
    +static int node_load[MAX_NUMNODES];
    /**
    * find_next_best_node - find the next node that should appear in a given node's fallback list
    * @node: node whose fallback list we're appending
    @@ -2060,7 +2061,7 @@ static int __meminitdata node_load[MAX_N
    * on them otherwise.
    * It returns -1 if no node is found.
    */
    -static int __meminit find_next_best_node(int node, nodemask_t *used_node_mask)
    +static int find_next_best_node(int node, nodemask_t *used_node_mask)
    {
    int n, val;
    int min_val = INT_MAX;
    @@ -2106,13 +2107,124 @@ static int __meminit find_next_best_node
    return best_node;
    }

    -static void __meminit build_zonelists(pg_data_t *pgdat)
    +/*
    + * numa_zonelist_order:
    + * 0 = automatic detection of better ordering.
    + * 1 = order by ([node] distance, -zonetype)
    + * 2 = order by (-zonetype, [node] distance)
    + */
    +#define ZONELIST_ORDER_AUTO 0
    +#define ZONELIST_ORDER_NODE 1
    +#define ZONELIST_ORDER_ZONE 2
    +static int zonelist_order = 0;
    +
    +/*
    + * command line option "numa_zonelist_order"
    + * = "[dD]efault | "0" - default, automatic configuration.
    + * = "[nN]ode"|"1" - order by node locality,
    + * then zone within node.
    + * = "[zZ]one"|"2" - order by zone, then by locality within zone
    + */
    +char numa_zonelist_order[NUMA_ZONELIST_ORDER_LEN] = "default";
    +
    +static int __parse_numa_zonelist_order(char *s)
    +{
    + if (*s == 'd' || *s == 'D' || *s == '0') {
    + strncpy(numa_zonelist_order, "default",
    + NUMA_ZONELIST_ORDER_LEN);
    + zonelist_order = ZONELIST_ORDER_AUTO;
    + } else if (*s == 'n' || *s == 'N' || *s == '1') {
    + strncpy(numa_zonelist_order, "node",
    + NUMA_ZONELIST_ORDER_LEN);
    + zonelist_order = ZONELIST_ORDER_NODE;
    + } else if (*s == 'z' || *s == 'Z' || *s == '2') {
    + strncpy(numa_zonelist_order, "zone",
    + NUMA_ZONELIST_ORDER_LEN);
    + zonelist_order = ZONELIST_ORDER_ZONE;
    + } else {
    + printk(KERN_WARNING
    + "Ignoring invalid numa_zonelist_order value: "
    + "%s\n", s);
    + return -EINVAL;
    + }
    + return 0;
    +}
    +
    +static __init int setup_numa_zonelist_order(char *s)
    +{
    + if (s)
    + return __parse_numa_zonelist_order(s);
    + return 0;
    +}
    +early_param("numa_zonelist_order", setup_numa_zonelist_order);
    +
    +/*
    + * Build zonelists ordered by node and zones within node.
    + * This results in maximum locality--normal zone overflows into local
    + * DMA zone, if any--but risks exhausting DMA zone.
    + */
    +static void build_zonelists_in_node_order(pg_data_t *pgdat, int node)
    {
    - int j, node, local_node;
    enum zone_type i;
    - int prev_node, load;
    + int j;
    + struct zonelist *zonelist;
    +
    + for (i = 0; i < MAX_NR_ZONES; i++) {
    + zonelist = pgdat->node_zonelists + i;
    + for (j = 0; zonelist->zones[j] != NULL; j++);
    +
    + j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
    + zonelist->zones[j] = NULL;
    + }
    +}
    +
    +/*
    + * Build zonelists ordered by zone and nodes within zones.
    + * This results in conserving DMA zone[s] until all Normal memory is
    + * exhausted, but results in overflowing to remote node while memory
    + * may still exist in local DMA zone.
    + */
    +static int node_order[MAX_NUMNODES];
    +
    +static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
    +{
    + enum zone_type i;
    + int pos, j, node;
    + int zone_type; /* needs to be signed */
    + struct zone *z;
    struct zonelist *zonelist;
    +
    + for (i = 0; i < MAX_NR_ZONES; i++) {
    + zonelist = pgdat->node_zonelists + i;
    + pos = 0;
    + for (zone_type = i; 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 (populated_zone(z))
    + zonelist->zones[pos++] = z;
    + }
    + }
    + zonelist->zones[pos] = NULL;
    + }
    +}
    +
    +static int estimate_zonelist_order(void)
    +{
    + /* dummy, just select node order. */
    + return ZONELIST_ORDER_NODE;
    +}
    +
    +
    +
    +static void build_zonelists(pg_data_t *pgdat)
    +{
    + int j, node, load;
    + enum zone_type i;
    nodemask_t used_mask;
    + int local_node, prev_node;
    + struct zonelist *zonelist;
    + int ordering;

    /* initialize zonelists */
    for (i = 0; i < MAX_NR_ZONES; i++) {
    @@ -2120,11 +2232,18 @@ static void __meminit build_zonelists(pg
    zonelist->zones[0] = NULL;
    }

    + ordering = zonelist_order;
    + if (ordering == ZONELIST_ORDER_AUTO)
    + ordering = estimate_zonelist_order();
    /* NUMA-aware ordering of nodes */
    local_node = pgdat->node_id;
    load = num_online_nodes();
    prev_node = local_node;
    nodes_clear(used_mask);
    +
    + memset(node_order, 0, sizeof(node_order));
    + j = 0;
    +
    while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
    int distance = node_distance(local_node, node);

    @@ -2140,18 +2259,20 @@ static void __meminit build_zonelists(pg
    * So adding penalty to the first node in same
    * distance group to make it round-robin.
    */
    -
    if (distance != node_distance(local_node, prev_node))
    - node_load[node] += load;
    + node_load[node] = load;
    +
    prev_node = node;
    load--;
    - for (i = 0; i < MAX_NR_ZONES; i++) {
    - zonelist = pgdat->node_zonelists + i;
    - for (j = 0; zonelist->zones[j] != NULL; j++);
    + if (ordering == ZONELIST_ORDER_NODE) /* default */
    + build_zonelists_in_node_order(pgdat, node);
    + else
    + node_order[j++] = node; /* remember order */
    + }

    - j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
    - zonelist->zones[j] = NULL;
    - }
    + if (ordering == ZONELIST_ORDER_ZONE) {
    + /* calculate node order -- i.e., DMA last! */
    + build_zonelists_in_zone_order(pgdat, j);
    }
    }

    @@ -2173,6 +2294,37 @@ static void __meminit build_zonelist_cac
    }
    }

    +/*
    + * sysctl handler for numa_zonelist_order
    + */
    +int numa_zonelist_order_handler(ctl_table *table, int write,
    + struct file *file, void __user *buffer, size_t *length,
    + loff_t *ppos)
    +{
    + char saved_string[NUMA_ZONELIST_ORDER_LEN];
    + int ret;
    +
    + if (write)
    + strncpy(saved_string, (char*)table->data,
    + NUMA_ZONELIST_ORDER_LEN);
    + ret = proc_dostring(table, write, file, buffer, length, ppos);
    + if (ret)
    + return ret;
    + if (write) {
    + int oldval = zonelist_order;
    + if (__parse_numa_zonelist_order((char*)table->data)) {
    + /*
    + * bogus value. restore saved string
    + */
    + strncpy((char*)table->data, saved_string,
    + NUMA_ZONELIST_ORDER_LEN);
    + zonelist_order = oldval;
    + } else if (oldval != zonelist_order)
    + build_all_zonelists();
    + }
    + return 0;
    +}
    +
    #else /* CONFIG_NUMA */

    static void __meminit build_zonelists(pg_data_t *pgdat)
    @@ -2222,7 +2374,7 @@ static void __meminit build_zonelist_cac
    #endif /* CONFIG_NUMA */

    /* return values int ....just for stop_machine_run() */
    -static int __meminit __build_all_zonelists(void *dummy)
    +static int __build_all_zonelists(void *dummy)
    {
    int nid;

    @@ -2233,12 +2385,13 @@ static int __meminit __build_all_zonelis
    return 0;
    }

    -void __meminit build_all_zonelists(void)
    +void build_all_zonelists(void)
    {
    if (system_state == SYSTEM_BOOTING) {
    __build_all_zonelists(NULL);
    cpuset_init_current_mems_allowed();
    } else {
    + memset(node_load, 0, sizeof(node_load));
    /* we have to stop all cpus to guaranntee there is no user
    of zonelist */
    stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
    Index: linux-2.6.21-rc7-mm2/include/linux/mmzone.h
    ===================================================================
    --- linux-2.6.21-rc7-mm2.orig/include/linux/mmzone.h
    +++ linux-2.6.21-rc7-mm2/include/linux/mmzone.h
    @@ -608,6 +608,11 @@ int sysctl_min_unmapped_ratio_sysctl_han
    int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
    struct file *, void __user *, size_t *, loff_t *);

    +extern int numa_zonelist_order_handler(struct ctl_table *, int,
    + struct file *, void __user *, size_t *, loff_t *);
    +extern char numa_zonelist_order[];
    +#define NUMA_ZONELIST_ORDER_LEN 16 /* string buffer size */
    +
    #include <linux/topology.h>
    /* Returns the number of the current Node. */
    #ifndef numa_node_id
    Index: linux-2.6.21-rc7-mm2/Documentation/kernel-parameters.txt
    ===================================================================
    --- linux-2.6.21-rc7-mm2.orig/Documentation/kernel-parameters.txt
    +++ linux-2.6.21-rc7-mm2/Documentation/kernel-parameters.txt
    @@ -1500,6 +1500,16 @@ and is between 256 and 4096 characters.
    Format: <reboot_mode>[,<reboot_mode2>[,...]]
    See arch/*/kernel/reboot.c or arch/*/kernel/process.c

    + numa_zonelist_order [KNL,BOOT]
    + Select memory allocation zonelist order for NUMA
    + platform. Default is automatic configuration.
    + "Node order" orders the zonelists by node [locality],
    + then zones within nodes. "Zone order" orders the
    + zonelists by zone,then nodes within the zone.
    + This moves DMA zone, if any, to the end of the
    + allocation lists.
    + See also Documentation/sysctl/vm.txt
    +
    reserve= [KNL,BUGS] Force the kernel to ignore some iomem area

    reservetop= [X86-32]
    Index: linux-2.6.21-rc7-mm2/Documentation/sysctl/vm.txt
    ===================================================================
    --- linux-2.6.21-rc7-mm2.orig/Documentation/sysctl/vm.txt
    +++ linux-2.6.21-rc7-mm2/Documentation/sysctl/vm.txt
    @@ -34,6 +34,7 @@ Currently, these files are in /proc/sys/
    - swap_prefetch
    - readahead_ratio
    - readahead_hit_rate
    +- numa_zonelist_order

    ==============================================================

    @@ -275,3 +276,34 @@ Possible values can be:
    The larger value, the more capabilities, with more possible overheads.

    The default value is 1.
    +
    +=============================================================
    +
    +numa_zonelist_order
    +
    +This sysctl is only for NUMA.
    +
    +numa_zonelist_order selects the order of the memory allocation zonelists.
    +The default order [a.k.a. "node order"] orders the zonelists by node, the
    +by zone within each node. The default is automatic configuration.
    +Specify "[Dd]fault" or "0" to request automatic configuration.
    +
    + For example, assume 2 Node NUMA. The "Node order" kernel memory allocation
    +order on Node(0) will be:
    +
    + Node(0)NORMAL -> Node(0)DMA -> Node(1)NORMAL -> Node(1)DMA(if any)
    +
    +Thus, allocations that request Node(0) NORMAL may overflow onto Node(0)DMA
    +first. This provides maximum locality, but risks exhausting all of DMA
    +memory while NORMAL memory exists elsewhere on the system. This can result
    +in OOM-KILL in ZONE_DMA. Secify "[Zz]one" or "1" to request zone order.
    +
    +If numa_zonelist_order is set to "node" order, the kernel memory allocation
    +order on Node(0) becomes:
    +
    + Node(0)NORMAL -> Node(1)NORMAL -> Node(0)DMA -> Node(1)DMA(if any)
    +
    +In this mode, DMA memory will be used in place of NORMAL memory, only when
    +all NORMAL zones are exhausted. Specify "[Nn]ode" or "2" for node order.
    +
    +The default value is 0.
    -
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