mm: scalable bdi statistics counters
Provide scalable per backing_dev_info statistics counters. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2 changed files with 109 additions and 3 deletions
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@ -8,6 +8,8 @@
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#ifndef _LINUX_BACKING_DEV_H
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#define _LINUX_BACKING_DEV_H
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#include <linux/percpu_counter.h>
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#include <linux/log2.h>
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#include <asm/atomic.h>
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struct page;
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@ -24,6 +26,12 @@ enum bdi_state {
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typedef int (congested_fn)(void *, int);
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enum bdi_stat_item {
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NR_BDI_STAT_ITEMS
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};
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#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
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struct backing_dev_info {
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unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
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unsigned long state; /* Always use atomic bitops on this */
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@ -32,15 +40,86 @@ struct backing_dev_info {
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void *congested_data; /* Pointer to aux data for congested func */
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void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
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void *unplug_io_data;
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struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
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};
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static inline int bdi_init(struct backing_dev_info *bdi)
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int bdi_init(struct backing_dev_info *bdi);
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void bdi_destroy(struct backing_dev_info *bdi);
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static inline void __add_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item, s64 amount)
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{
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return 0;
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__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
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}
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static inline void bdi_destroy(struct backing_dev_info *bdi)
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static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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__add_bdi_stat(bdi, item, 1);
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}
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static inline void inc_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__inc_bdi_stat(bdi, item);
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local_irq_restore(flags);
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}
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static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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__add_bdi_stat(bdi, item, -1);
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}
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static inline void dec_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__dec_bdi_stat(bdi, item);
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local_irq_restore(flags);
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}
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static inline s64 bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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return percpu_counter_read_positive(&bdi->bdi_stat[item]);
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}
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static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
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}
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static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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s64 sum;
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unsigned long flags;
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local_irq_save(flags);
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sum = __bdi_stat_sum(bdi, item);
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local_irq_restore(flags);
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return sum;
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}
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/*
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* maximal error of a stat counter.
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*/
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static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
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{
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#ifdef CONFIG_SMP
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return nr_cpu_ids * BDI_STAT_BATCH;
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#else
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return 1;
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#endif
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}
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/*
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@ -5,6 +5,33 @@
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#include <linux/sched.h>
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#include <linux/module.h>
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int bdi_init(struct backing_dev_info *bdi)
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{
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int i, j;
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int err;
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
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err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
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if (err) {
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for (j = 0; j < i; j++)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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break;
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}
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}
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return err;
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}
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EXPORT_SYMBOL(bdi_init);
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void bdi_destroy(struct backing_dev_info *bdi)
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{
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int i;
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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}
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EXPORT_SYMBOL(bdi_destroy);
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static wait_queue_head_t congestion_wqh[2] = {
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
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