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![Jack Steiner](/assets/img/avatar_default.png)
We have observed several workloads running on multi-node systems where memory is assigned unevenly across the nodes in the system. There are numerous reasons for this but one is the round-robin rotor in cpuset_mem_spread_node(). For example, a simple test that writes a multi-page file will allocate pages on nodes 0 2 4 6 ... Odd nodes are skipped. (Sometimes it allocates on odd nodes & skips even nodes). An example is shown below. The program "lfile" writes a file consisting of 10 pages. The program then mmaps the file & uses get_mempolicy(..., MPOL_F_NODE) to determine the nodes where the file pages were allocated. The output is shown below: # ./lfile allocated on nodes: 2 4 6 0 1 2 6 0 2 There is a single rotor that is used for allocating both file pages & slab pages. Writing the file allocates both a data page & a slab page (buffer_head). This advances the RR rotor 2 nodes for each page allocated. A quick confirmation seems to confirm this is the cause of the uneven allocation: # echo 0 >/dev/cpuset/memory_spread_slab # ./lfile allocated on nodes: 6 7 8 9 0 1 2 3 4 5 This patch introduces a second rotor that is used for slab allocations. Signed-off-by: Jack Steiner <steiner@sgi.com> Acked-by: 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>
241 lines
5.6 KiB
C
241 lines
5.6 KiB
C
#ifndef _LINUX_CPUSET_H
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#define _LINUX_CPUSET_H
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/*
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* cpuset interface
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*
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* Copyright (C) 2003 BULL SA
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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*/
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/nodemask.h>
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#include <linux/cgroup.h>
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#include <linux/mm.h>
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#ifdef CONFIG_CPUSETS
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extern int number_of_cpusets; /* How many cpusets are defined in system? */
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extern int cpuset_init(void);
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extern void cpuset_init_smp(void);
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extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
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extern int cpuset_cpus_allowed_fallback(struct task_struct *p);
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extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
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#define cpuset_current_mems_allowed (current->mems_allowed)
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void cpuset_init_current_mems_allowed(void);
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int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
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extern int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask);
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extern int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask);
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static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
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{
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return number_of_cpusets <= 1 ||
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__cpuset_node_allowed_softwall(node, gfp_mask);
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}
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static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
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{
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return number_of_cpusets <= 1 ||
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__cpuset_node_allowed_hardwall(node, gfp_mask);
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}
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static inline int cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
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{
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return cpuset_node_allowed_softwall(zone_to_nid(z), gfp_mask);
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}
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static inline int cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
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{
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return cpuset_node_allowed_hardwall(zone_to_nid(z), gfp_mask);
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}
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extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
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const struct task_struct *tsk2);
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#define cpuset_memory_pressure_bump() \
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do { \
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if (cpuset_memory_pressure_enabled) \
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__cpuset_memory_pressure_bump(); \
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} while (0)
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extern int cpuset_memory_pressure_enabled;
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extern void __cpuset_memory_pressure_bump(void);
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extern const struct file_operations proc_cpuset_operations;
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struct seq_file;
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extern void cpuset_task_status_allowed(struct seq_file *m,
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struct task_struct *task);
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extern int cpuset_mem_spread_node(void);
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extern int cpuset_slab_spread_node(void);
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static inline int cpuset_do_page_mem_spread(void)
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{
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return current->flags & PF_SPREAD_PAGE;
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}
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static inline int cpuset_do_slab_mem_spread(void)
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{
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return current->flags & PF_SPREAD_SLAB;
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}
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extern int current_cpuset_is_being_rebound(void);
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extern void rebuild_sched_domains(void);
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extern void cpuset_print_task_mems_allowed(struct task_struct *p);
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/*
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* reading current mems_allowed and mempolicy in the fastpath must protected
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* by get_mems_allowed()
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*/
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static inline void get_mems_allowed(void)
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{
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current->mems_allowed_change_disable++;
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/*
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* ensure that reading mems_allowed and mempolicy happens after the
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* update of ->mems_allowed_change_disable.
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*
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* the write-side task finds ->mems_allowed_change_disable is not 0,
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* and knows the read-side task is reading mems_allowed or mempolicy,
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* so it will clear old bits lazily.
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*/
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smp_mb();
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}
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static inline void put_mems_allowed(void)
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{
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/*
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* ensure that reading mems_allowed and mempolicy before reducing
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* mems_allowed_change_disable.
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*
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* the write-side task will know that the read-side task is still
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* reading mems_allowed or mempolicy, don't clears old bits in the
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* nodemask.
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*/
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smp_mb();
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--ACCESS_ONCE(current->mems_allowed_change_disable);
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}
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static inline void set_mems_allowed(nodemask_t nodemask)
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{
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task_lock(current);
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current->mems_allowed = nodemask;
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task_unlock(current);
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}
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#else /* !CONFIG_CPUSETS */
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static inline int cpuset_init(void) { return 0; }
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static inline void cpuset_init_smp(void) {}
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static inline void cpuset_cpus_allowed(struct task_struct *p,
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struct cpumask *mask)
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{
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cpumask_copy(mask, cpu_possible_mask);
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}
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static inline int cpuset_cpus_allowed_fallback(struct task_struct *p)
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{
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cpumask_copy(&p->cpus_allowed, cpu_possible_mask);
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return cpumask_any(cpu_active_mask);
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}
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static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
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{
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return node_possible_map;
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}
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#define cpuset_current_mems_allowed (node_states[N_HIGH_MEMORY])
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static inline void cpuset_init_current_mems_allowed(void) {}
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static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
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{
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return 1;
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}
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static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
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const struct task_struct *tsk2)
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{
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return 1;
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}
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static inline void cpuset_memory_pressure_bump(void) {}
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static inline void cpuset_task_status_allowed(struct seq_file *m,
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struct task_struct *task)
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{
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}
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static inline int cpuset_mem_spread_node(void)
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{
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return 0;
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}
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static inline int cpuset_slab_spread_node(void)
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{
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return 0;
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}
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static inline int cpuset_do_page_mem_spread(void)
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{
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return 0;
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}
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static inline int cpuset_do_slab_mem_spread(void)
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{
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return 0;
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}
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static inline int current_cpuset_is_being_rebound(void)
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{
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return 0;
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}
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static inline void rebuild_sched_domains(void)
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{
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partition_sched_domains(1, NULL, NULL);
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}
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static inline void cpuset_print_task_mems_allowed(struct task_struct *p)
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{
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}
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static inline void set_mems_allowed(nodemask_t nodemask)
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{
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}
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static inline void get_mems_allowed(void)
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{
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}
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static inline void put_mems_allowed(void)
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{
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}
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#endif /* !CONFIG_CPUSETS */
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#endif /* _LINUX_CPUSET_H */
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