/* * 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. Finetuning 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* for cli()/sti() */ #include /* for copy_to/from_user */ #include #include /* * 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 */ 72, /* freepages.low */ 96 /* freepages.high */ }; /* 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 */ 32, 4, /* Aging cluster */ 8192, 8192, /* Pageout and bufferout weights */ }; swapstat_t swapstats = {0}; buffer_mem_t buffer_mem = { 3, /* minimum percent buffer */ 10, /* borrow percent buffer */ 30 /* maximum percent buffer */ }; buffer_mem_t page_cache = { 10, /* minimum percent page cache */ 30, /* borrow percent page cache */ 75 /* maximum */ };