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kernel/linux-imx6_3.14.28/mm/quicklist.c 2.4 KB
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  /*
   * Quicklist support.
   *
   * Quicklists are light weight lists of pages that have a defined state
   * on alloc and free. Pages must be in the quicklist specific defined state
   * (zero by default) when the page is freed. It seems that the initial idea
   * for such lists first came from Dave Miller and then various other people
   * improved on it.
   *
   * Copyright (C) 2007 SGI,
   * 	Christoph Lameter <clameter@sgi.com>
   * 		Generalized, added support for multiple lists and
   * 		constructors / destructors.
   */
  #include <linux/kernel.h>
  
  #include <linux/gfp.h>
  #include <linux/mm.h>
  #include <linux/mmzone.h>
  #include <linux/quicklist.h>
  
  DEFINE_PER_CPU(struct quicklist [CONFIG_NR_QUICK], quicklist);
  
  #define FRACTION_OF_NODE_MEM	16
  
  static unsigned long max_pages(unsigned long min_pages)
  {
  	unsigned long node_free_pages, max;
  	int node = numa_node_id();
  	struct zone *zones = NODE_DATA(node)->node_zones;
  	int num_cpus_on_node;
  
  	node_free_pages =
  #ifdef CONFIG_ZONE_DMA
  		zone_page_state(&zones[ZONE_DMA], NR_FREE_PAGES) +
  #endif
  #ifdef CONFIG_ZONE_DMA32
  		zone_page_state(&zones[ZONE_DMA32], NR_FREE_PAGES) +
  #endif
  		zone_page_state(&zones[ZONE_NORMAL], NR_FREE_PAGES);
  
  	max = node_free_pages / FRACTION_OF_NODE_MEM;
  
  	num_cpus_on_node = cpumask_weight(cpumask_of_node(node));
  	max /= num_cpus_on_node;
  
  	return max(max, min_pages);
  }
  
  static long min_pages_to_free(struct quicklist *q,
  	unsigned long min_pages, long max_free)
  {
  	long pages_to_free;
  
  	pages_to_free = q->nr_pages - max_pages(min_pages);
  
  	return min(pages_to_free, max_free);
  }
  
  /*
   * Trim down the number of pages in the quicklist
   */
  void quicklist_trim(int nr, void (*dtor)(void *),
  	unsigned long min_pages, unsigned long max_free)
  {
  	long pages_to_free;
  	struct quicklist *q;
  
  	q = &get_cpu_var(quicklist)[nr];
  	if (q->nr_pages > min_pages) {
  		pages_to_free = min_pages_to_free(q, min_pages, max_free);
  
  		while (pages_to_free > 0) {
  			/*
  			 * We pass a gfp_t of 0 to quicklist_alloc here
  			 * because we will never call into the page allocator.
  			 */
  			void *p = quicklist_alloc(nr, 0, NULL);
  
  			if (dtor)
  				dtor(p);
  			free_page((unsigned long)p);
  			pages_to_free--;
  		}
  	}
  	put_cpu_var(quicklist);
  }
  
  unsigned long quicklist_total_size(void)
  {
  	unsigned long count = 0;
  	int cpu;
  	struct quicklist *ql, *q;
  
  	for_each_online_cpu(cpu) {
  		ql = per_cpu(quicklist, cpu);
  		for (q = ql; q < ql + CONFIG_NR_QUICK; q++)
  			count += q->nr_pages;
  	}
  	return count;
  }