include/linux/quicklist.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef LINUX_QUICKLIST_H
   3 #define LINUX_QUICKLIST_H
   4 /*
   5  * Fast allocations and disposal of pages. Pages must be in the condition
   6  * as needed after allocation when they are freed. Per cpu lists of pages
   7  * are kept that only contain node local pages.
   8  *
   9  * (C) 2007, SGI. Christoph Lameter <cl@linux.com>
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/gfp.h>
  13 #include <linux/percpu.h>
  14
  15 #ifdef CONFIG_QUICKLIST
  16
  17 struct quicklist {
  18         void *page;
  19         int nr_pages;
  20 };
  21
  22 DECLARE_PER_CPU(struct quicklist, quicklist)[CONFIG_NR_QUICK];
  23
  24 /*
  25  * The two key functions quicklist_alloc and quicklist_free are inline so
  26  * that they may be custom compiled for the platform.
  27  * Specifying a NULL ctor can remove constructor support. Specifying
  28  * a constant quicklist allows the determination of the exact address
  29  * in the per cpu area.
  30  *
  31  * The fast patch in quicklist_alloc touched only a per cpu cacheline and
  32  * the first cacheline of the page itself. There is minmal overhead involved.
  33  */
  34 static inline void *quicklist_alloc(int nr, gfp_t flags, void (*ctor)(void *))
  35 {
  36         struct quicklist *q;
  37         void **p = NULL;
  38
  39         q =&get_cpu_var(quicklist)[nr];
  40         p = q->page;
  41         if (likely(p)) {
  42                 q->page = p[0];
  43                 p[0] = NULL;
  44                 q->nr_pages--;
  45         }
  46         put_cpu_var(quicklist);
  47         if (likely(p))
  48                 return p;
  49
  50         p = (void *)__get_free_page(flags | __GFP_ZERO);
  51         if (ctor && p)
  52                 ctor(p);
  53         return p;
  54 }
  55
  56 static inline void __quicklist_free(int nr, void (*dtor)(void *), void *p,
  57         struct page *page)
  58 {
  59         struct quicklist *q;
  60
  61         q = &get_cpu_var(quicklist)[nr];
  62         *(void **)p = q->page;
  63         q->page = p;
  64         q->nr_pages++;
  65         put_cpu_var(quicklist);
  66 }
  67
  68 static inline void quicklist_free(int nr, void (*dtor)(void *), void *pp)
  69 {
  70         __quicklist_free(nr, dtor, pp, virt_to_page(pp));
  71 }
  72
  73 static inline void quicklist_free_page(int nr, void (*dtor)(void *),
  74                                                         struct page *page)
  75 {
  76         __quicklist_free(nr, dtor, page_address(page), page);
  77 }
  78
  79 void quicklist_trim(int nr, void (*dtor)(void *),
  80         unsigned long min_pages, unsigned long max_free);
  81
  82 unsigned long quicklist_total_size(void);
  83
  84 #else
  85
  86 static inline unsigned long quicklist_total_size(void)
  87 {
  88         return 0;
  89 }
  90
  91 #endif
  92
  93 #endif /* LINUX_QUICKLIST_H */
  94