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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 | /* * linux/mm/swap.c * * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds */ /* * This file should contain most things doing the swapping from/to disk. * Started 18.12.91 * * Swap aging added 23.2.95, Stephen Tweedie. */ #include <linux/mm.h> #include <linux/sched.h> #include <linux/head.h> #include <linux/kernel.h> #include <linux/kernel_stat.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/stat.h> #include <linux/swap.h> #include <linux/fs.h> #include <linux/swapctl.h> #include <linux/pagemap.h> #include <asm/dma.h> #include <asm/system.h> /* for cli()/sti() */ #include <asm/segment.h> /* for memcpy_to/fromfs */ #include <asm/bitops.h> #include <asm/pgtable.h> /* * We identify three levels of free memory. We never let free mem * fall below the min_free_pages except for atomic allocations. We * start background swapping if we fall below free_pages_high free * pages, and we begin intensive swapping below free_pages_low. * * Keep these three variables contiguous for sysctl(2). */ int min_free_pages = 20; int free_pages_low = 30; int free_pages_high = 40; /* We track the number of pages currently being asynchronously swapped out, so that we don't try to swap TOO many pages out at once */ int nr_async_pages = 0; /* * Constants for the page aging mechanism: the maximum age (actually, * the maximum "youthfulness"); the quanta by which pages rejuvinate * and age; and the initial age for new pages. */ swap_control_t swap_control = { 20, 3, 1, 3, /* Page aging */ 10, 2, 2, 4, /* Buffer aging */ 32, 4, /* Aging cluster */ 8192, 8192, /* Pageout and bufferout weights */ -200, /* Buffer grace */ 1, 1, /* Buffs/pages to free */ RCL_ROUND_ROBIN /* Balancing policy */ }; swapstat_t swapstats = {0}; /* General swap control */ /* Parse the kernel command line "swap=" option at load time: */ void swap_setup(char *str, int *ints) { int * swap_vars[8] = { &MAX_PAGE_AGE, &PAGE_ADVANCE, &PAGE_DECLINE, &PAGE_INITIAL_AGE, &AGE_CLUSTER_FRACT, &AGE_CLUSTER_MIN, &PAGEOUT_WEIGHT, &BUFFEROUT_WEIGHT }; int i; for (i=0; i < ints[0] && i < 8; i++) { if (ints[i+1]) *(swap_vars[i]) = ints[i+1]; } } /* Parse the kernel command line "buff=" option at load time: */ void buff_setup(char *str, int *ints) { int * buff_vars[6] = { &MAX_BUFF_AGE, &BUFF_ADVANCE, &BUFF_DECLINE, &BUFF_INITIAL_AGE, &BUFFEROUT_WEIGHT, &BUFFERMEM_GRACE }; int i; for (i=0; i < ints[0] && i < 6; i++) { if (ints[i+1]) *(buff_vars[i]) = ints[i+1]; } } |