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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/uaccess.h> /* for copy_to/from_user */
#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 = 48;
int free_pages_low = 72;
int free_pages_high = 96;
/* 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 = ATOMIC_INIT(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];
}
}
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