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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/mm.h>

#include <linux/mmzone.h>

#include <linux/module.h>

#include <linux/quicklist.h>

DEFINE_PER_CPU(struct quicklist, quicklist)[CONFIG_NR_QUICK];

#define FRACTION_OF_NODE_MEM    16

static unsigned long max_pages(unsigned long min_pages)

{

        unsigned long node_free_pages, max;

        struct zone *zones = NODE_DATA(numa_node_id())->node_zones;

        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;

        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;

}