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/*

 *  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 */

atomic_t nr_async_pages = 0;

/*

 * Constants for the page aging mechanism: the maximum age (actually,

 * the maximum "youthfulness"); the quanta by which pages rejuvenate

 * 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];

        }

}