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/*
* linux/mm/swap.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*/
/*
* This file contains the default values for the opereation of the
* Linux VM subsystem. Fine-tuning documentation can be found in
* linux/Documentation/sysctl/vm.txt.
* Started 18.12.91
* Swap aging added 23.2.95, Stephen Tweedie.
* Buffermem limits added 12.3.98, Rik van Riel.
*/
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/swapctl.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <asm/dma.h>
#include <asm/uaccess.h> /* for copy_to/from_user */
#include <asm/pgtable.h>
/*
* We identify three levels of free memory. We never let free mem
* fall below the freepages.min except for atomic allocations. We
* start background swapping if we fall below freepages.high free
* pages, and we begin intensive swapping below freepages.low.
*
* These values are there to keep GCC from complaining. Actual
* initialization is done in mm/page_alloc.c or arch/sparc(64)/mm/init.c.
*/
freepages_t freepages = {
48, /* freepages.min */
96, /* freepages.low */
144 /* freepages.high */
};
/* How many pages do we try to swap or page in/out together? */
int page_cluster = 4; /* Default value modified in swap_setup() */
/* 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);
buffer_mem_t buffer_mem = {
2, /* minimum percent buffer */
10, /* borrow percent buffer */
60 /* maximum percent buffer */
};
buffer_mem_t page_cache = {
2, /* minimum percent page cache */
15, /* borrow percent page cache */
75 /* maximum */
};
pager_daemon_t pager_daemon = {
512, /* base number for calculating the number of tries */
SWAP_CLUSTER_MAX, /* minimum number of tries */
SWAP_CLUSTER_MAX, /* do swap I/O in clusters of this size */
};
/*
* Perform any setup for the swap system
*/
void __init swap_setup(void)
{
/* Use a smaller cluster for memory <16MB or <32MB */
if (num_physpages < ((16 * 1024 * 1024) >> PAGE_SHIFT))
page_cluster = 2;
else if (num_physpages < ((32 * 1024 * 1024) >> PAGE_SHIFT))
page_cluster = 3;
else
page_cluster = 4;
}
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