diff options
Diffstat (limited to 'sys/vm')
-rw-r--r-- | sys/vm/vm_zeroidle.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/sys/vm/vm_zeroidle.c b/sys/vm/vm_zeroidle.c new file mode 100644 index 0000000..c1361de --- /dev/null +++ b/sys/vm/vm_zeroidle.c @@ -0,0 +1,117 @@ +/*- + * Copyright (c) 1994 John Dyson + * Copyright (c) 2001 Matt Dillon + * + * All rights reserved. Terms for use and redistribution + * are covered by the BSD Copyright as found in /usr/src/COPYRIGHT. + * + * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91 + * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ + * $FreeBSD$ + */ + +#include "opt_npx.h" +#ifdef PC98 +#include "opt_pc98.h" +#endif +#include "opt_reset.h" +#include "opt_isa.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/proc.h> +#include <sys/bio.h> +#include <sys/buf.h> +#include <sys/vnode.h> +#include <sys/vmmeter.h> +#include <sys/kernel.h> +#include <sys/ktr.h> +#include <sys/mutex.h> +#include <sys/smp.h> +#include <sys/sysctl.h> +#include <sys/unistd.h> + +#include <machine/cpu.h> +#include <machine/md_var.h> +#include <machine/pcb.h> +#include <machine/pcb_ext.h> +#include <machine/vm86.h> + +#include <vm/vm.h> +#include <vm/vm_param.h> +#include <sys/lock.h> +#include <vm/vm_kern.h> +#include <vm/vm_page.h> +#include <vm/vm_map.h> +#include <vm/vm_extern.h> + +#include <sys/user.h> + +#ifdef PC98 +#include <pc98/pc98/pc98.h> +#else +#include <i386/isa/isa.h> +#endif + +SYSCTL_DECL(_vm_stats_misc); + +static int cnt_prezero; + +SYSCTL_INT(_vm_stats_misc, OID_AUTO, + cnt_prezero, CTLFLAG_RD, &cnt_prezero, 0, ""); + +/* + * Implement the pre-zeroed page mechanism. + * This routine is called from the idle loop. + */ + +#define ZIDLE_LO(v) ((v) * 2 / 3) +#define ZIDLE_HI(v) ((v) * 4 / 5) + +int +vm_page_zero_idle(void) +{ + static int free_rover; + static int zero_state; + vm_page_t m; + + /* + * Attempt to maintain approximately 1/2 of our free pages in a + * PG_ZERO'd state. Add some hysteresis to (attempt to) avoid + * generally zeroing a page when the system is near steady-state. + * Otherwise we might get 'flutter' during disk I/O / IPC or + * fast sleeps. We also do not want to be continuously zeroing + * pages because doing so may flush our L1 and L2 caches too much. + */ + + if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count)) + return(0); + if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) + return(0); + + if (mtx_trylock(&Giant)) { + zero_state = 0; + m = vm_pageq_find(PQ_FREE, free_rover, FALSE); + if (m != NULL && (m->flags & PG_ZERO) == 0) { + vm_page_queues[m->queue].lcnt--; + TAILQ_REMOVE(&vm_page_queues[m->queue].pl, m, pageq); + m->queue = PQ_NONE; + pmap_zero_page(VM_PAGE_TO_PHYS(m)); + vm_page_flag_set(m, PG_ZERO); + m->queue = PQ_FREE + m->pc; + vm_page_queues[m->queue].lcnt++; + TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m, + pageq); + ++vm_page_zero_count; + ++cnt_prezero; + if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) + zero_state = 1; + } + free_rover = (free_rover + PQ_PRIME2) & PQ_L2_MASK; + mtx_unlock(&Giant); + return (1); + } + return(0); +} + |