forked from luck/tmp_suning_uos_patched
cpusets: randomize node rotor used in cpuset_mem_spread_node()
Some workloads that create a large number of small files tend to assign too many pages to node 0 (multi-node systems). Part of the reason is that the rotor (in cpuset_mem_spread_node()) used to assign nodes starts at node 0 for newly created tasks. This patch changes the rotor to be initialized to a random node number of the cpuset. [akpm@linux-foundation.org: fix layout] [Lee.Schermerhorn@hp.com: Define stub numa_random() for !NUMA configuration] Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Paul Menage <menage@google.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -2,6 +2,7 @@
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#include <linux/topology.h>
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#include <linux/module.h>
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#include <linux/bootmem.h>
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#include <linux/random.h>
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#ifdef CONFIG_DEBUG_PER_CPU_MAPS
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# define DBG(x...) printk(KERN_DEBUG x)
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@ -65,3 +66,19 @@ const struct cpumask *cpumask_of_node(int node)
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}
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EXPORT_SYMBOL(cpumask_of_node);
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#endif
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/*
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* Return the bit number of a random bit set in the nodemask.
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* (returns -1 if nodemask is empty)
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*/
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int __node_random(const nodemask_t *maskp)
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{
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int w, bit = -1;
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w = nodes_weight(*maskp);
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if (w)
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bit = bitmap_ord_to_pos(maskp->bits,
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get_random_int() % w, MAX_NUMNODES);
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return bit;
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}
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EXPORT_SYMBOL(__node_random);
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@ -141,6 +141,7 @@ extern int bitmap_find_free_region(unsigned long *bitmap, int bits, int order);
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extern void bitmap_release_region(unsigned long *bitmap, int pos, int order);
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extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);
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extern void bitmap_copy_le(void *dst, const unsigned long *src, int nbits);
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extern int bitmap_ord_to_pos(const unsigned long *bitmap, int n, int bits);
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#define BITMAP_LAST_WORD_MASK(nbits) \
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( \
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@ -66,6 +66,8 @@
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* int num_online_nodes() Number of online Nodes
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* int num_possible_nodes() Number of all possible Nodes
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*
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* int node_random(mask) Random node with set bit in mask
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*
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* int node_online(node) Is some node online?
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* int node_possible(node) Is some node possible?
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*
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@ -430,6 +432,10 @@ static inline void node_set_offline(int nid)
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node_clear_state(nid, N_ONLINE);
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nr_online_nodes = num_node_state(N_ONLINE);
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}
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#define node_random(mask) __node_random(&(mask))
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extern int __node_random(const nodemask_t *maskp);
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#else
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static inline int node_state(int node, enum node_states state)
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@ -460,6 +466,8 @@ static inline int num_node_state(enum node_states state)
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#define node_set_online(node) node_set_state((node), N_ONLINE)
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#define node_set_offline(node) node_clear_state((node), N_ONLINE)
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static inline int node_random(const nodemask_t mask) { return 0; }
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#endif
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#define node_online_map node_states[N_ONLINE]
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@ -1079,6 +1079,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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}
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mpol_fix_fork_child_flag(p);
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#endif
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#ifdef CONFIG_CPUSETS
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p->cpuset_mem_spread_rotor = node_random(p->mems_allowed);
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p->cpuset_slab_spread_rotor = node_random(p->mems_allowed);
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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p->irq_events = 0;
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#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
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@ -672,7 +672,7 @@ static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
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*
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* The bit positions 0 through @bits are valid positions in @buf.
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*/
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static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
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int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
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{
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int pos = 0;
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