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quicklist.h
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1 #ifndef LINUX_QUICKLIST_H
2 #define LINUX_QUICKLIST_H
3 /*
4  * Fast allocations and disposal of pages. Pages must be in the condition
5  * as needed after allocation when they are freed. Per cpu lists of pages
6  * are kept that only contain node local pages.
7  *
8  * (C) 2007, SGI. Christoph Lameter <[email protected]>
9  */
10 #include <linux/kernel.h>
11 #include <linux/gfp.h>
12 #include <linux/percpu.h>
13 
14 #ifdef CONFIG_QUICKLIST
15 
16 struct quicklist {
17  void *page;
18  int nr_pages;
19 };
20 
21 DECLARE_PER_CPU(struct quicklist, quicklist)[CONFIG_NR_QUICK];
22 
23 /*
24  * The two key functions quicklist_alloc and quicklist_free are inline so
25  * that they may be custom compiled for the platform.
26  * Specifying a NULL ctor can remove constructor support. Specifying
27  * a constant quicklist allows the determination of the exact address
28  * in the per cpu area.
29  *
30  * The fast patch in quicklist_alloc touched only a per cpu cacheline and
31  * the first cacheline of the page itself. There is minmal overhead involved.
32  */
33 static inline void *quicklist_alloc(int nr, gfp_t flags, void (*ctor)(void *))
34 {
35  struct quicklist *q;
36  void **p = NULL;
37 
38  q =&get_cpu_var(quicklist)[nr];
39  p = q->page;
40  if (likely(p)) {
41  q->page = p[0];
42  p[0] = NULL;
43  q->nr_pages--;
44  }
45  put_cpu_var(quicklist);
46  if (likely(p))
47  return p;
48 
49  p = (void *)__get_free_page(flags | __GFP_ZERO);
50  if (ctor && p)
51  ctor(p);
52  return p;
53 }
54 
55 static inline void __quicklist_free(int nr, void (*dtor)(void *), void *p,
56  struct page *page)
57 {
58  struct quicklist *q;
59 
60  q = &get_cpu_var(quicklist)[nr];
61  *(void **)p = q->page;
62  q->page = p;
63  q->nr_pages++;
64  put_cpu_var(quicklist);
65 }
66 
67 static inline void quicklist_free(int nr, void (*dtor)(void *), void *pp)
68 {
69  __quicklist_free(nr, dtor, pp, virt_to_page(pp));
70 }
71 
72 static inline void quicklist_free_page(int nr, void (*dtor)(void *),
73  struct page *page)
74 {
75  __quicklist_free(nr, dtor, page_address(page), page);
76 }
77 
78 void quicklist_trim(int nr, void (*dtor)(void *),
79  unsigned long min_pages, unsigned long max_free);
80 
81 unsigned long quicklist_total_size(void);
82 
83 #else
84 
85 static inline unsigned long quicklist_total_size(void)
86 {
87  return 0;
88 }
89 
90 #endif
91 
92 #endif /* LINUX_QUICKLIST_H */
93