Pileus Git - ~andy/linux/blob - drivers/staging/android/lowmemorykiller.c

   1 /* drivers/misc/lowmemorykiller.c
   2  *
   3  * Copyright (C) 2007-2008 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/oom.h>
  20 #include <linux/sched.h>
  21
  22 static uint32_t lowmem_debug_level = 2;
  23 static int lowmem_adj[6] = {
  24         0,
  25         1,
  26         6,
  27         12,
  28 };
  29 static int lowmem_adj_size = 4;
  30 static size_t lowmem_minfree[6] = {
  31         3 * 512,        /* 6MB */
  32         2 * 1024,       /* 8MB */
  33         4 * 1024,       /* 16MB */
  34         16 * 1024,      /* 64MB */
  35 };
  36 static int lowmem_minfree_size = 4;
  37
  38 #define lowmem_print(level, x...)                       \
  39         do {                                            \
  40                 if (lowmem_debug_level >= (level))      \
  41                         printk(x);                      \
  42         } while (0)
  43
  44 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
  45 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
  46                          S_IRUGO | S_IWUSR);
  47 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
  48                          S_IRUGO | S_IWUSR);
  49 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
  50
  51 static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
  52 {
  53         struct task_struct *p;
  54         struct task_struct *selected = NULL;
  55         int rem = 0;
  56         int tasksize;
  57         int i;
  58         int min_adj = OOM_ADJUST_MAX + 1;
  59         int selected_tasksize = 0;
  60         int selected_oom_adj;
  61         int array_size = ARRAY_SIZE(lowmem_adj);
  62         int other_free = global_page_state(NR_FREE_PAGES);
  63         int other_file = global_page_state(NR_FILE_PAGES);
  64
  65         if (lowmem_adj_size < array_size)
  66                 array_size = lowmem_adj_size;
  67         if (lowmem_minfree_size < array_size)
  68                 array_size = lowmem_minfree_size;
  69         for (i = 0; i < array_size; i++) {
  70                 if (other_free < lowmem_minfree[i] &&
  71                     other_file < lowmem_minfree[i]) {
  72                         min_adj = lowmem_adj[i];
  73                         break;
  74                 }
  75         }
  76         if (nr_to_scan > 0)
  77                 lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
  78                              nr_to_scan, gfp_mask, other_free, other_file,
  79                              min_adj);
  80         rem = global_page_state(NR_ACTIVE_ANON) +
  81                 global_page_state(NR_ACTIVE_FILE) +
  82                 global_page_state(NR_INACTIVE_ANON) +
  83                 global_page_state(NR_INACTIVE_FILE);
  84         if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
  85                 lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
  86                              nr_to_scan, gfp_mask, rem);
  87                 return rem;
  88         }
  89         selected_oom_adj = min_adj;
  90
  91         read_lock(&tasklist_lock);
  92         for_each_process(p) {
  93                 struct mm_struct *mm;
  94                 int oom_adj;
  95
  96                 task_lock(p);
  97                 mm = p->mm;
  98                 if (!mm) {
  99                         task_unlock(p);
 100                         continue;
 101                 }
 102                 oom_adj = mm->oom_adj;
 103                 if (oom_adj < min_adj) {
 104                         task_unlock(p);
 105                         continue;
 106                 }
 107                 tasksize = get_mm_rss(mm);
 108                 task_unlock(p);
 109                 if (tasksize <= 0)
 110                         continue;
 111                 if (selected) {
 112                         if (oom_adj < selected_oom_adj)
 113                                 continue;
 114                         if (oom_adj == selected_oom_adj &&
 115                             tasksize <= selected_tasksize)
 116                                 continue;
 117                 }
 118                 selected = p;
 119                 selected_tasksize = tasksize;
 120                 selected_oom_adj = oom_adj;
 121                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 122                              p->pid, p->comm, oom_adj, tasksize);
 123         }
 124         if (selected) {
 125                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 126                              selected->pid, selected->comm,
 127                              selected_oom_adj, selected_tasksize);
 128                 force_sig(SIGKILL, selected);
 129                 rem -= selected_tasksize;
 130         }
 131         lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
 132                      nr_to_scan, gfp_mask, rem);
 133         read_unlock(&tasklist_lock);
 134         return rem;
 135 }
 136
 137 static struct shrinker lowmem_shrinker = {
 138         .shrink = lowmem_shrink,
 139         .seeks = DEFAULT_SEEKS * 16
 140 };
 141
 142 static int __init lowmem_init(void)
 143 {
 144         register_shrinker(&lowmem_shrinker);
 145         return 0;
 146 }
 147
 148 static void __exit lowmem_exit(void)
 149 {
 150         unregister_shrinker(&lowmem_shrinker);
 151 }
 152
 153 module_init(lowmem_init);
 154 module_exit(lowmem_exit);
 155
 156 MODULE_LICENSE("GPL");
 157