1/*
2 * Quicklist support.
3 *
4 * Quicklists are light weight lists of pages that have a defined state
5 * on alloc and free. Pages must be in the quicklist specific defined state
6 * (zero by default) when the page is freed. It seems that the initial idea
7 * for such lists first came from Dave Miller and then various other people
8 * improved on it.
9 *
10 * Copyright (C) 2007 SGI,
11 * 	Christoph Lameter <clameter@sgi.com>
12 * 		Generalized, added support for multiple lists and
13 * 		constructors / destructors.
14 */
15#include <linux/kernel.h>
16
17#include <linux/gfp.h>
18#include <linux/mm.h>
19#include <linux/mmzone.h>
20#include <linux/quicklist.h>
21
22DEFINE_PER_CPU(struct quicklist [CONFIG_NR_QUICK], quicklist);
23
24#define FRACTION_OF_NODE_MEM	16
25
26static unsigned long max_pages(unsigned long min_pages)
27{
28	unsigned long node_free_pages, max;
29	int node = numa_node_id();
30	struct zone *zones = NODE_DATA(node)->node_zones;
31	int num_cpus_on_node;
32
33	node_free_pages =
34#ifdef CONFIG_ZONE_DMA
35		zone_page_state(&zones[ZONE_DMA], NR_FREE_PAGES) +
36#endif
37#ifdef CONFIG_ZONE_DMA32
38		zone_page_state(&zones[ZONE_DMA32], NR_FREE_PAGES) +
39#endif
40		zone_page_state(&zones[ZONE_NORMAL], NR_FREE_PAGES);
41
42	max = node_free_pages / FRACTION_OF_NODE_MEM;
43
44	num_cpus_on_node = cpumask_weight(cpumask_of_node(node));
45	max /= num_cpus_on_node;
46
47	return max(max, min_pages);
48}
49
50static long min_pages_to_free(struct quicklist *q,
51	unsigned long min_pages, long max_free)
52{
53	long pages_to_free;
54
55	pages_to_free = q->nr_pages - max_pages(min_pages);
56
57	return min(pages_to_free, max_free);
58}
59
60/*
61 * Trim down the number of pages in the quicklist
62 */
63void quicklist_trim(int nr, void (*dtor)(void *),
64	unsigned long min_pages, unsigned long max_free)
65{
66	long pages_to_free;
67	struct quicklist *q;
68
69	q = &get_cpu_var(quicklist)[nr];
70	if (q->nr_pages > min_pages) {
71		pages_to_free = min_pages_to_free(q, min_pages, max_free);
72
73		while (pages_to_free > 0) {
74			/*
75			 * We pass a gfp_t of 0 to quicklist_alloc here
76			 * because we will never call into the page allocator.
77			 */
78			void *p = quicklist_alloc(nr, 0, NULL);
79
80			if (dtor)
81				dtor(p);
82			free_page((unsigned long)p);
83			pages_to_free--;
84		}
85	}
86	put_cpu_var(quicklist);
87}
88
89unsigned long quicklist_total_size(void)
90{
91	unsigned long count = 0;
92	int cpu;
93	struct quicklist *ql, *q;
94
95	for_each_online_cpu(cpu) {
96		ql = per_cpu(quicklist, cpu);
97		for (q = ql; q < ql + CONFIG_NR_QUICK; q++)
98			count += q->nr_pages;
99	}
100	return count;
101}
102
103