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Commit a whole cluster of last minute critical (and one cosmetic) fixes
[unix-history] / sys / vm / swap_pager.c
/*
* Copyright (c) 1994 John S. Dyson
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
* from: @(#)swap_pager.c 7.4 (Berkeley) 5/7/91
*
* $Id: swap_pager.c,v 1.26 1994/04/26 00:42:37 davidg Exp $
*/
/*
* Mostly rewritten by John Dyson with help from David Greenman, 12-Jan-1994
*/
#include "param.h"
#include "proc.h"
#include "buf.h"
#include "kernel.h"
#include "systm.h"
#include "specdev.h"
#include "vnode.h"
#include "malloc.h"
#include "queue.h"
#include "rlist.h"
#include "vm_param.h"
#include "queue.h"
#include "lock.h"
#include "vm.h"
#include "vm_prot.h"
#include "vm_object.h"
#include "vm_page.h"
#include "vm_pageout.h"
#include "swap_pager.h"
#include "vm_map.h"
#ifndef NPENDINGIO
#define NPENDINGIO 16
#endif
extern int nswbuf;
int nswiodone;
extern int vm_pageout_rate_limit;
static int cleandone;
extern int hz;
int swap_pager_full;
extern vm_map_t pager_map;
extern int vm_pageout_pages_needed;
extern int vm_swap_size;
#define MAX_PAGEOUT_CLUSTER 8
struct swpagerclean {
queue_head_t spc_list;
int spc_flags;
struct buf *spc_bp;
sw_pager_t spc_swp;
vm_offset_t spc_kva;
vm_offset_t spc_altkva;
int spc_count;
vm_page_t spc_m[MAX_PAGEOUT_CLUSTER];
} swcleanlist [NPENDINGIO] ;
typedef struct swpagerclean *swp_clean_t;
extern vm_map_t kernel_map;
/* spc_flags values */
#define SPC_ERROR 0x01
#define SWB_EMPTY (-1)
queue_head_t swap_pager_done; /* list of compileted page cleans */
queue_head_t swap_pager_inuse; /* list of pending page cleans */
queue_head_t swap_pager_free; /* list of free pager clean structs */
queue_head_t swap_pager_list; /* list of "named" anon regions */
queue_head_t swap_pager_un_list; /* list of "unnamed" anon pagers */
#define SWAP_FREE_NEEDED 0x1 /* need a swap block */
int swap_pager_needflags;
struct rlist *swapfrag;
static queue_head_t *swp_qs[]={
&swap_pager_list, &swap_pager_un_list, (queue_head_t *) 0
};
int swap_pager_putmulti();
struct pagerops swappagerops = {
swap_pager_init,
swap_pager_alloc,
swap_pager_dealloc,
swap_pager_getpage,
swap_pager_getmulti,
swap_pager_putpage,
swap_pager_putmulti,
swap_pager_haspage
};
extern int nswbuf;
int npendingio = NPENDINGIO;
int pendingiowait;
int require_swap_init;
void swap_pager_finish();
int dmmin, dmmax;
extern int vm_page_count;
struct buf * getpbuf() ;
void relpbuf(struct buf *bp) ;
static inline void swapsizecheck() {
if( vm_swap_size < 128*btodb(NBPG)) {
if( swap_pager_full)
printf("swap_pager: out of space\n");
swap_pager_full = 1;
} else if( vm_swap_size > 192*btodb(NBPG))
swap_pager_full = 0;
}
void
swap_pager_init()
{
extern int dmmin, dmmax;
dfltpagerops = &swappagerops;
queue_init(&swap_pager_list);
queue_init(&swap_pager_un_list);
/*
* Initialize clean lists
*/
queue_init(&swap_pager_inuse);
queue_init(&swap_pager_done);
queue_init(&swap_pager_free);
require_swap_init = 1;
/*
* Calculate the swap allocation constants.
*/
dmmin = CLBYTES/DEV_BSIZE;
dmmax = btodb(SWB_NPAGES*NBPG)*2;
}
/*
* Allocate a pager structure and associated resources.
* Note that if we are called from the pageout daemon (handle == NULL)
* we should not wait for memory as it could resulting in deadlock.
*/
vm_pager_t
swap_pager_alloc(handle, size, prot, offset)
caddr_t handle;
register vm_size_t size;
vm_prot_t prot;
vm_offset_t offset;
{
register vm_pager_t pager;
register sw_pager_t swp;
int waitok;
int i,j;
if (require_swap_init) {
register swp_clean_t spc;
struct buf *bp;
/*
* kva's are allocated here so that we dont need to keep
* doing kmem_alloc pageables at runtime
*/
for (i = 0, spc = swcleanlist; i < npendingio ; i++, spc++) {
spc->spc_kva = kmem_alloc_pageable(pager_map, NBPG);
if (!spc->spc_kva) {
break;
}
spc->spc_bp = malloc( sizeof( *bp), M_TEMP,
M_NOWAIT);
if (!spc->spc_bp) {
kmem_free_wakeup(pager_map, spc->spc_kva, NBPG);
break;
}
spc->spc_flags = 0;
queue_enter(&swap_pager_free, spc, swp_clean_t, spc_list);
}
require_swap_init = 0;
if( size == 0)
return(NULL);
}
/*
* If this is a "named" anonymous region, look it up and
* return the appropriate pager if it exists.
*/
if (handle) {
pager = vm_pager_lookup(&swap_pager_list, handle);
if (pager != NULL) {
/*
* Use vm_object_lookup to gain a reference
* to the object and also to remove from the
* object cache.
*/
if (vm_object_lookup(pager) == NULL)
panic("swap_pager_alloc: bad object");
return(pager);
}
}
if (swap_pager_full) {
return(NULL);
}
/*
* Pager doesn't exist, allocate swap management resources
* and initialize.
*/
waitok = handle ? M_WAITOK : M_NOWAIT;
pager = (vm_pager_t)malloc(sizeof *pager, M_VMPAGER, waitok);
if (pager == NULL)
return(NULL);
swp = (sw_pager_t)malloc(sizeof *swp, M_VMPGDATA, waitok);
if (swp == NULL) {
free((caddr_t)pager, M_VMPAGER);
return(NULL);
}
size = round_page(size);
swp->sw_osize = size;
swp->sw_nblocks = (btodb(size) + btodb(SWB_NPAGES * NBPG) - 1) / btodb(SWB_NPAGES*NBPG);
swp->sw_blocks = (sw_blk_t)
malloc(swp->sw_nblocks*sizeof(*swp->sw_blocks),
M_VMPGDATA, waitok);
if (swp->sw_blocks == NULL) {
free((caddr_t)swp, M_VMPGDATA);
free((caddr_t)pager, M_VMPAGER);
return(NULL);
}
for (i = 0; i < swp->sw_nblocks; i++) {
swp->sw_blocks[i].swb_valid = 0;
swp->sw_blocks[i].swb_locked = 0;
for (j = 0; j < SWB_NPAGES; j++)
swp->sw_blocks[i].swb_block[j] = SWB_EMPTY;
}
swp->sw_poip = 0;
if (handle) {
vm_object_t object;
swp->sw_flags = SW_NAMED;
queue_enter(&swap_pager_list, pager, vm_pager_t, pg_list);
/*
* Consistant with other pagers: return with object
* referenced. Can't do this with handle == NULL
* since it might be the pageout daemon calling.
*/
object = vm_object_allocate(size);
vm_object_enter(object, pager);
vm_object_setpager(object, pager, 0, FALSE);
} else {
swp->sw_flags = 0;
queue_init(&pager->pg_list);
queue_enter(&swap_pager_un_list, pager, vm_pager_t, pg_list);
}
pager->pg_handle = handle;
pager->pg_ops = &swappagerops;
pager->pg_type = PG_SWAP;
pager->pg_data = (caddr_t)swp;
return(pager);
}
/*
* returns disk block associated with pager and offset
* additionally, as a side effect returns a flag indicating
* if the block has been written
*/
static int *
swap_pager_diskaddr(swp, offset, valid)
sw_pager_t swp;
vm_offset_t offset;
int *valid;
{
register sw_blk_t swb;
int ix;
if (valid)
*valid = 0;
ix = offset / (SWB_NPAGES*NBPG);
if (swp->sw_blocks == NULL || ix >= swp->sw_nblocks) {
return(FALSE);
}
swb = &swp->sw_blocks[ix];
ix = (offset % (SWB_NPAGES*NBPG)) / NBPG;
if (valid)
*valid = swb->swb_valid & (1<<ix);
return &swb->swb_block[ix];
}
/*
* Utility routine to set the valid (written) bit for
* a block associated with a pager and offset
*/
static void
swap_pager_setvalid(swp, offset, valid)
sw_pager_t swp;
vm_offset_t offset;
int valid;
{
register sw_blk_t swb;
int ix;
ix = offset / (SWB_NPAGES*NBPG);
if (swp->sw_blocks == NULL || ix >= swp->sw_nblocks)
return;
swb = &swp->sw_blocks[ix];
ix = (offset % (SWB_NPAGES*NBPG)) / NBPG;
if (valid)
swb->swb_valid |= (1 << ix);
else
swb->swb_valid &= ~(1 << ix);
return;
}
/*
* this routine allocates swap space with a fragmentation
* minimization policy.
*/
int
swap_pager_getswapspace( unsigned amount, unsigned *rtval) {
unsigned tmpalloc;
unsigned nblocksfrag = btodb(SWB_NPAGES*NBPG);
if( amount < nblocksfrag) {
if( rlist_alloc(&swapfrag, amount, rtval))
return 1;
if( !rlist_alloc(&swapmap, nblocksfrag, &tmpalloc))
return 0;
rlist_free( &swapfrag, tmpalloc+amount, tmpalloc + nblocksfrag - 1);
*rtval = tmpalloc;
return 1;
}
if( !rlist_alloc(&swapmap, amount, rtval))
return 0;
else
return 1;
}
/*
* this routine frees swap space with a fragmentation
* minimization policy.
*/
void
swap_pager_freeswapspace( unsigned from, unsigned to) {
unsigned nblocksfrag = btodb(SWB_NPAGES*NBPG);
unsigned tmpalloc;
if( ((to + 1) - from) >= nblocksfrag) {
while( (from + nblocksfrag) <= to + 1) {
rlist_free(&swapmap, from, from + nblocksfrag - 1);
from += nblocksfrag;
}
}
if( from >= to)
return;
rlist_free(&swapfrag, from, to);
while( rlist_alloc(&swapfrag, nblocksfrag, &tmpalloc)) {
rlist_free(&swapmap, tmpalloc, tmpalloc + nblocksfrag-1);
}
}
/*
* this routine frees swap blocks from a specified pager
*/
void
_swap_pager_freespace(swp, start, size)
sw_pager_t swp;
vm_offset_t start;
vm_offset_t size;
{
vm_offset_t i;
int s;
s = splbio();
for (i = start; i < round_page(start + size - 1); i += NBPG) {
int valid;
int *addr = swap_pager_diskaddr(swp, i, &valid);
if (addr && *addr != SWB_EMPTY) {
swap_pager_freeswapspace(*addr, *addr+btodb(NBPG) - 1);
if( valid) {
vm_swap_size += btodb(NBPG);
swap_pager_setvalid(swp, i, 0);
}
*addr = SWB_EMPTY;
}
}
swapsizecheck();
splx(s);
}
void
swap_pager_freespace(pager, start, size)
vm_pager_t pager;
vm_offset_t start;
vm_offset_t size;
{
_swap_pager_freespace((sw_pager_t) pager->pg_data, start, size);
}
/*
* swap_pager_reclaim frees up over-allocated space from all pagers
* this eliminates internal fragmentation due to allocation of space
* for segments that are never swapped to. It has been written so that
* it does not block until the rlist_free operation occurs; it keeps
* the queues consistant.
*/
/*
* Maximum number of blocks (pages) to reclaim per pass
*/
#define MAXRECLAIM 256
void
swap_pager_reclaim()
{
vm_pager_t p;
sw_pager_t swp;
int i, j, k;
int s;
int reclaimcount;
static int reclaims[MAXRECLAIM];
static int in_reclaim;
/*
* allow only one process to be in the swap_pager_reclaim subroutine
*/
s = splbio();
if (in_reclaim) {
tsleep((caddr_t) &in_reclaim, PSWP, "swrclm", 0);
splx(s);
return;
}
in_reclaim = 1;
reclaimcount = 0;
/* for each pager queue */
for (k = 0; swp_qs[k]; k++) {
p = (vm_pager_t) queue_first(swp_qs[k]);
while (reclaimcount < MAXRECLAIM &&
!queue_end(swp_qs[k], (queue_entry_t) p)) {
/*
* see if any blocks associated with a pager has been
* allocated but not used (written)
*/
swp = (sw_pager_t) p->pg_data;
for (i = 0; i < swp->sw_nblocks; i++) {
sw_blk_t swb = &swp->sw_blocks[i];
if( swb->swb_locked)
continue;
for (j = 0; j < SWB_NPAGES; j++) {
if (swb->swb_block[j] != SWB_EMPTY &&
(swb->swb_valid & (1 << j)) == 0) {
reclaims[reclaimcount++] = swb->swb_block[j];
swb->swb_block[j] = SWB_EMPTY;
if (reclaimcount >= MAXRECLAIM)
goto rfinished;
}
}
}
p = (vm_pager_t) queue_next(&p->pg_list);
}
}
rfinished:
/*
* free the blocks that have been added to the reclaim list
*/
for (i = 0; i < reclaimcount; i++) {
swap_pager_freeswapspace(reclaims[i], reclaims[i]+btodb(NBPG) - 1);
swapsizecheck();
wakeup((caddr_t) &in_reclaim);
}
splx(s);
in_reclaim = 0;
wakeup((caddr_t) &in_reclaim);
}
/*
* swap_pager_copy copies blocks from one pager to another and
* destroys the source pager
*/
void
swap_pager_copy(srcpager, srcoffset, dstpager, dstoffset, offset)
vm_pager_t srcpager;
vm_offset_t srcoffset;
vm_pager_t dstpager;
vm_offset_t dstoffset;
vm_offset_t offset;
{
sw_pager_t srcswp, dstswp;
vm_offset_t i;
int s;
srcswp = (sw_pager_t) srcpager->pg_data;
dstswp = (sw_pager_t) dstpager->pg_data;
/*
* remove the source pager from the swap_pager internal queue
*/
s = splbio();
if (srcswp->sw_flags & SW_NAMED) {
queue_remove(&swap_pager_list, srcpager, vm_pager_t, pg_list);
srcswp->sw_flags &= ~SW_NAMED;
} else {
queue_remove(&swap_pager_un_list, srcpager, vm_pager_t, pg_list);
}
while (srcswp->sw_poip) {
tsleep((caddr_t)srcswp, PVM, "spgout", 0);
}
splx(s);
/*
* clean all of the pages that are currently active and finished
*/
(void) swap_pager_clean();
s = splbio();
/*
* clear source block before destination object
* (release allocated space)
*/
for (i = 0; i < offset + srcoffset; i += NBPG) {
int valid;
int *addr = swap_pager_diskaddr(srcswp, i, &valid);
if (addr && *addr != SWB_EMPTY) {
swap_pager_freeswapspace(*addr, *addr+btodb(NBPG) - 1);
if( valid)
vm_swap_size += btodb(NBPG);
swapsizecheck();
*addr = SWB_EMPTY;
}
}
/*
* transfer source to destination
*/
for (i = 0; i < dstswp->sw_osize; i += NBPG) {
int srcvalid, dstvalid;
int *srcaddrp = swap_pager_diskaddr(srcswp, i + offset + srcoffset,
&srcvalid);
int *dstaddrp;
/*
* see if the source has space allocated
*/
if (srcaddrp && *srcaddrp != SWB_EMPTY) {
/*
* if the source is valid and the dest has no space, then
* copy the allocation from the srouce to the dest.
*/
if (srcvalid) {
dstaddrp = swap_pager_diskaddr(dstswp, i + dstoffset, &dstvalid);
/*
* if the dest already has a valid block, deallocate the
* source block without copying.
*/
if (!dstvalid && dstaddrp && *dstaddrp != SWB_EMPTY) {
swap_pager_freeswapspace(*dstaddrp, *dstaddrp+btodb(NBPG) - 1);
*dstaddrp = SWB_EMPTY;
}
if (dstaddrp && *dstaddrp == SWB_EMPTY) {
*dstaddrp = *srcaddrp;
*srcaddrp = SWB_EMPTY;
swap_pager_setvalid(dstswp, i + dstoffset, 1);
vm_swap_size -= btodb(NBPG);
}
}
/*
* if the source is not empty at this point, then deallocate the space.
*/
if (*srcaddrp != SWB_EMPTY) {
swap_pager_freeswapspace(*srcaddrp, *srcaddrp+btodb(NBPG) - 1);
if( srcvalid)
vm_swap_size += btodb(NBPG);
*srcaddrp = SWB_EMPTY;
}
}
}
/*
* deallocate the rest of the source object
*/
for (i = dstswp->sw_osize + offset + srcoffset; i < srcswp->sw_osize; i += NBPG) {
int valid;
int *srcaddrp = swap_pager_diskaddr(srcswp, i, &valid);
if (srcaddrp && *srcaddrp != SWB_EMPTY) {
swap_pager_freeswapspace(*srcaddrp, *srcaddrp+btodb(NBPG) - 1);
if( valid)
vm_swap_size += btodb(NBPG);
*srcaddrp = SWB_EMPTY;
}
}
swapsizecheck();
splx(s);
free((caddr_t)srcswp->sw_blocks, M_VMPGDATA);
srcswp->sw_blocks = 0;
free((caddr_t)srcswp, M_VMPGDATA);
srcpager->pg_data = 0;
free((caddr_t)srcpager, M_VMPAGER);
return;
}
void
swap_pager_dealloc(pager)
vm_pager_t pager;
{
register int i,j;
register sw_blk_t bp;
register sw_pager_t swp;
int s;
/*
* Remove from list right away so lookups will fail if we
* block for pageout completion.
*/
s = splbio();
swp = (sw_pager_t) pager->pg_data;
if (swp->sw_flags & SW_NAMED) {
queue_remove(&swap_pager_list, pager, vm_pager_t, pg_list);
swp->sw_flags &= ~SW_NAMED;
} else {
queue_remove(&swap_pager_un_list, pager, vm_pager_t, pg_list);
}
/*
* Wait for all pageouts to finish and remove
* all entries from cleaning list.
*/
while (swp->sw_poip) {
tsleep((caddr_t)swp, PVM, "swpout", 0);
}
splx(s);
(void) swap_pager_clean();
/*
* Free left over swap blocks
*/
s = splbio();
for (i = 0, bp = swp->sw_blocks; i < swp->sw_nblocks; i++, bp++) {
for (j = 0; j < SWB_NPAGES; j++)
if (bp->swb_block[j] != SWB_EMPTY) {
swap_pager_freeswapspace((unsigned)bp->swb_block[j],
(unsigned)bp->swb_block[j] + btodb(NBPG) - 1);
if( bp->swb_valid & (1<<j))
vm_swap_size += btodb(NBPG);
bp->swb_block[j] = SWB_EMPTY;
}
}
splx(s);
swapsizecheck();
/*
* Free swap management resources
*/
free((caddr_t)swp->sw_blocks, M_VMPGDATA);
swp->sw_blocks = 0;
free((caddr_t)swp, M_VMPGDATA);
pager->pg_data = 0;
free((caddr_t)pager, M_VMPAGER);
}
/*
* swap_pager_getmulti can get multiple pages.
*/
int
swap_pager_getmulti(pager, m, count, reqpage, sync)
vm_pager_t pager;
vm_page_t *m;
int count;
int reqpage;
boolean_t sync;
{
if( reqpage >= count)
panic("swap_pager_getmulti: reqpage >= count\n");
return swap_pager_input((sw_pager_t) pager->pg_data, m, count, reqpage);
}
/*
* swap_pager_getpage gets individual pages
*/
int
swap_pager_getpage(pager, m, sync)
vm_pager_t pager;
vm_page_t m;
boolean_t sync;
{
vm_page_t marray[1];
marray[0] = m;
return swap_pager_input((sw_pager_t)pager->pg_data, marray, 1, 0);
}
int
swap_pager_putmulti(pager, m, c, sync, rtvals)
vm_pager_t pager;
vm_page_t *m;
int c;
boolean_t sync;
int *rtvals;
{
int flags;
if (pager == NULL) {
(void) swap_pager_clean();
return VM_PAGER_OK;
}
flags = B_WRITE;
if (!sync)
flags |= B_ASYNC;
return swap_pager_output((sw_pager_t)pager->pg_data, m, c, flags, rtvals);
}
/*
* swap_pager_putpage writes individual pages
*/
int
swap_pager_putpage(pager, m, sync)
vm_pager_t pager;
vm_page_t m;
boolean_t sync;
{
int flags;
vm_page_t marray[1];
int rtvals[1];
if (pager == NULL) {
(void) swap_pager_clean();
return VM_PAGER_OK;
}
marray[0] = m;
flags = B_WRITE;
if (!sync)
flags |= B_ASYNC;
swap_pager_output((sw_pager_t)pager->pg_data, marray, 1, flags, rtvals);
return rtvals[0];
}
static inline int
const swap_pager_block_index(swp, offset)
sw_pager_t swp;
vm_offset_t offset;
{
return (offset / (SWB_NPAGES*NBPG));
}
static inline int
const swap_pager_block_offset(swp, offset)
sw_pager_t swp;
vm_offset_t offset;
{
return ((offset % (NBPG*SWB_NPAGES)) / NBPG);
}
/*
* _swap_pager_haspage returns TRUE if the pager has data that has
* been written out.
*/
static boolean_t
_swap_pager_haspage(swp, offset)
sw_pager_t swp;
vm_offset_t offset;
{
register sw_blk_t swb;
int ix;
ix = offset / (SWB_NPAGES*NBPG);
if (swp->sw_blocks == NULL || ix >= swp->sw_nblocks) {
return(FALSE);
}
swb = &swp->sw_blocks[ix];
ix = (offset % (SWB_NPAGES*NBPG)) / NBPG;
if (swb->swb_block[ix] != SWB_EMPTY) {
if (swb->swb_valid & (1 << ix))
return TRUE;
}
return(FALSE);
}
/*
* swap_pager_haspage is the externally accessible version of
* _swap_pager_haspage above. this routine takes a vm_pager_t
* for an argument instead of sw_pager_t.
*/
boolean_t
swap_pager_haspage(pager, offset)
vm_pager_t pager;
vm_offset_t offset;
{
return _swap_pager_haspage((sw_pager_t) pager->pg_data, offset);
}
/*
* swap_pager_freepage is a convienience routine that clears the busy
* bit and deallocates a page.
*/
static void
swap_pager_freepage(m)
vm_page_t m;
{
PAGE_WAKEUP(m);
vm_page_free(m);
}
/*
* swap_pager_ridpages is a convienience routine that deallocates all
* but the required page. this is usually used in error returns that
* need to invalidate the "extra" readahead pages.
*/
static void
swap_pager_ridpages(m, count, reqpage)
vm_page_t *m;
int count;
int reqpage;
{
int i;
for (i = 0; i < count; i++)
if (i != reqpage)
swap_pager_freepage(m[i]);
}
int swapwritecount=0;
/*
* swap_pager_iodone1 is the completion routine for both reads and async writes
*/
void
swap_pager_iodone1(bp)
struct buf *bp;
{
bp->b_flags |= B_DONE;
bp->b_flags &= ~B_ASYNC;
wakeup((caddr_t)bp);
/*
if ((bp->b_flags & B_READ) == 0)
vwakeup(bp);
*/
}
int
swap_pager_input(swp, m, count, reqpage)
register sw_pager_t swp;
vm_page_t *m;
int count, reqpage;
{
register struct buf *bp;
sw_blk_t swb[count];
register int s;
int i;
boolean_t rv;
vm_offset_t kva, off[count];
swp_clean_t spc;
vm_offset_t paging_offset;
vm_object_t object;
int reqaddr[count];
int first, last;
int failed;
int reqdskregion;
object = m[reqpage]->object;
paging_offset = object->paging_offset;
/*
* First determine if the page exists in the pager if this is
* a sync read. This quickly handles cases where we are
* following shadow chains looking for the top level object
* with the page.
*/
if (swp->sw_blocks == NULL) {
swap_pager_ridpages(m, count, reqpage);
return(VM_PAGER_FAIL);
}
for(i = 0; i < count; i++) {
vm_offset_t foff = m[i]->offset + paging_offset;
int ix = swap_pager_block_index(swp, foff);
if (ix >= swp->sw_nblocks) {
int j;
if( i <= reqpage) {
swap_pager_ridpages(m, count, reqpage);
return(VM_PAGER_FAIL);
}
for(j = i; j < count; j++) {
swap_pager_freepage(m[j]);
}
count = i;
break;
}
swb[i] = &swp->sw_blocks[ix];
off[i] = swap_pager_block_offset(swp, foff);
reqaddr[i] = swb[i]->swb_block[off[i]];
}
/* make sure that our required input request is existant */
if (reqaddr[reqpage] == SWB_EMPTY ||
(swb[reqpage]->swb_valid & (1 << off[reqpage])) == 0) {
swap_pager_ridpages(m, count, reqpage);
return(VM_PAGER_FAIL);
}
reqdskregion = reqaddr[reqpage] / dmmax;
/*
* search backwards for the first contiguous page to transfer
*/
failed = 0;
first = 0;
for (i = reqpage - 1; i >= 0; --i) {
if ( failed || (reqaddr[i] == SWB_EMPTY) ||
(swb[i]->swb_valid & (1 << off[i])) == 0 ||
(reqaddr[i] != (reqaddr[reqpage] + (i - reqpage) * btodb(NBPG))) ||
((reqaddr[i] / dmmax) != reqdskregion)) {
failed = 1;
swap_pager_freepage(m[i]);
if (first == 0)
first = i + 1;
}
}
/*
* search forwards for the last contiguous page to transfer
*/
failed = 0;
last = count;
for (i = reqpage + 1; i < count; i++) {
if ( failed || (reqaddr[i] == SWB_EMPTY) ||
(swb[i]->swb_valid & (1 << off[i])) == 0 ||
(reqaddr[i] != (reqaddr[reqpage] + (i - reqpage) * btodb(NBPG))) ||
((reqaddr[i] / dmmax) != reqdskregion)) {
failed = 1;
swap_pager_freepage(m[i]);
if (last == count)
last = i;
}
}
count = last;
if (first != 0) {
for (i = first; i < count; i++) {
m[i-first] = m[i];
reqaddr[i-first] = reqaddr[i];
off[i-first] = off[i];
}
count -= first;
reqpage -= first;
}
++swb[reqpage]->swb_locked;
/*
* at this point:
* "m" is a pointer to the array of vm_page_t for paging I/O
* "count" is the number of vm_page_t entries represented by "m"
* "object" is the vm_object_t for I/O
* "reqpage" is the index into "m" for the page actually faulted
*/
spc = NULL; /* we might not use an spc data structure */
kva = 0;
/*
* we allocate a new kva for transfers > 1 page
* but for transfers == 1 page, the swap_pager_free list contains
* entries that have pre-allocated kva's (for efficiency).
*/
if (count > 1) {
kva = kmem_alloc_pageable(pager_map, count*NBPG);
}
if (!kva) {
/*
* if a kva has not been allocated, we can only do a one page transfer,
* so we free the other pages that might have been allocated by
* vm_fault.
*/
swap_pager_ridpages(m, count, reqpage);
m[0] = m[reqpage];
reqaddr[0] = reqaddr[reqpage];
count = 1;
reqpage = 0;
/*
* get a swap pager clean data structure, block until we get it
*/
if (queue_empty(&swap_pager_free)) {
s = splbio();
if( curproc == pageproc)
(void) swap_pager_clean();
else
wakeup((caddr_t) &vm_pages_needed);
while (queue_empty(&swap_pager_free)) {
swap_pager_needflags |= SWAP_FREE_NEEDED;
tsleep((caddr_t)&swap_pager_free,
PVM, "swpfre", 0);
if( curproc == pageproc)
(void) swap_pager_clean();
else
wakeup((caddr_t) &vm_pages_needed);
}
splx(s);
}
queue_remove_first(&swap_pager_free, spc, swp_clean_t, spc_list);
kva = spc->spc_kva;
}
/*
* map our page(s) into kva for input
*/
for (i = 0; i < count; i++) {
pmap_kenter( kva + NBPG * i, VM_PAGE_TO_PHYS(m[i]));
}
pmap_update();
/*
* Get a swap buffer header and perform the IO
*/
if( spc) {
bp = spc->spc_bp;
bzero(bp, sizeof *bp);
bp->b_spc = spc;
} else {
bp = getpbuf();
}
s = splbio();
bp->b_flags = B_BUSY | B_READ | B_CALL;
bp->b_iodone = swap_pager_iodone1;
bp->b_proc = &proc0; /* XXX (but without B_PHYS set this is ok) */
bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
bp->b_un.b_addr = (caddr_t) kva;
bp->b_blkno = reqaddr[0];
bp->b_bcount = NBPG*count;
bp->b_bufsize = NBPG*count;
VHOLD(swapdev_vp);
bp->b_vp = swapdev_vp;
if (swapdev_vp->v_type == VBLK)
bp->b_dev = swapdev_vp->v_rdev;
swp->sw_piip++;
/*
* perform the I/O
*/
VOP_STRATEGY(bp);
/*
* wait for the sync I/O to complete
*/
while ((bp->b_flags & B_DONE) == 0) {
tsleep((caddr_t)bp, PVM, "swread", 0);
}
rv = (bp->b_flags & B_ERROR) ? VM_PAGER_FAIL : VM_PAGER_OK;
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_DIRTY|B_CALL|B_DONE);
--swp->sw_piip;
if (swp->sw_piip == 0)
wakeup((caddr_t) swp);
if (bp->b_vp)
brelvp(bp);
splx(s);
--swb[reqpage]->swb_locked;
/*
* remove the mapping for kernel virtual
*/
pmap_remove(vm_map_pmap(pager_map), kva, kva + count * NBPG);
if (spc) {
/*
* if we have used an spc, we need to free it.
*/
queue_enter(&swap_pager_free, spc, swp_clean_t, spc_list);
if (swap_pager_needflags & SWAP_FREE_NEEDED) {
swap_pager_needflags &= ~SWAP_FREE_NEEDED;
wakeup((caddr_t)&swap_pager_free);
}
} else {
/*
* free the kernel virtual addresses
*/
kmem_free_wakeup(pager_map, kva, count * NBPG);
/*
* release the physical I/O buffer
*/
relpbuf(bp);
/*
* finish up input if everything is ok
*/
if( rv == VM_PAGER_OK) {
for (i = 0; i < count; i++) {
pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
m[i]->flags |= PG_CLEAN;
m[i]->flags &= ~PG_LAUNDRY;
if (i != reqpage) {
/*
* whether or not to leave the page activated
* is up in the air, but we should put the page
* on a page queue somewhere. (it already is in
* the object).
* After some emperical results, it is best
* to deactivate the readahead pages.
*/
vm_page_deactivate(m[i]);
/*
* just in case someone was asking for this
* page we now tell them that it is ok to use
*/
m[i]->flags &= ~PG_FAKE;
PAGE_WAKEUP(m[i]);
}
}
if( swap_pager_full) {
_swap_pager_freespace( swp, m[0]->offset+paging_offset, count*NBPG);
}
} else {
swap_pager_ridpages(m, count, reqpage);
}
}
return(rv);
}
int
swap_pager_output(swp, m, count, flags, rtvals)
register sw_pager_t swp;
vm_page_t *m;
int count;
int flags;
int *rtvals;
{
register struct buf *bp;
sw_blk_t swb[count];
register int s;
int i, j, ix;
boolean_t rv;
vm_offset_t kva, off, foff;
swp_clean_t spc;
vm_offset_t paging_offset;
vm_object_t object;
int reqaddr[count];
int failed;
/*
if( count > 1)
printf("off: 0x%x, count: %d\n", m[0]->offset, count);
*/
spc = NULL;
object = m[0]->object;
paging_offset = object->paging_offset;
failed = 0;
for(j=0;j<count;j++) {
foff = m[j]->offset + paging_offset;
ix = swap_pager_block_index(swp, foff);
swb[j] = 0;
if( swp->sw_blocks == NULL || ix >= swp->sw_nblocks) {
rtvals[j] = VM_PAGER_FAIL;
failed = 1;
continue;
} else {
rtvals[j] = VM_PAGER_OK;
}
swb[j] = &swp->sw_blocks[ix];
++swb[j]->swb_locked;
if( failed) {
rtvals[j] = VM_PAGER_FAIL;
continue;
}
off = swap_pager_block_offset(swp, foff);
reqaddr[j] = swb[j]->swb_block[off];
if( reqaddr[j] == SWB_EMPTY) {
int blk;
int tries;
int ntoget;
tries = 0;
s = splbio();
/*
* if any other pages have been allocated in this block, we
* only try to get one page.
*/
for (i = 0; i < SWB_NPAGES; i++) {
if (swb[j]->swb_block[i] != SWB_EMPTY)
break;
}
ntoget = (i == SWB_NPAGES) ? SWB_NPAGES : 1;
/*
* this code is alittle conservative, but works
* (the intent of this code is to allocate small chunks
* for small objects)
*/
if( (m[j]->offset == 0) && (ntoget*NBPG > object->size)) {
ntoget = (object->size + (NBPG-1))/NBPG;
}
retrygetspace:
if (!swap_pager_full && ntoget > 1 &&
swap_pager_getswapspace(ntoget * btodb(NBPG), &blk)) {
for (i = 0; i < ntoget; i++) {
swb[j]->swb_block[i] = blk + btodb(NBPG) * i;
swb[j]->swb_valid = 0;
}
reqaddr[j] = swb[j]->swb_block[off];
} else if (!swap_pager_getswapspace(btodb(NBPG),
&swb[j]->swb_block[off])) {
/*
* if the allocation has failed, we try to reclaim space and
* retry.
*/
if (++tries == 1) {
swap_pager_reclaim();
goto retrygetspace;
}
rtvals[j] = VM_PAGER_TRYAGAIN;
failed = 1;
} else {
reqaddr[j] = swb[j]->swb_block[off];
swb[j]->swb_valid &= ~(1<<off);
}
splx(s);
}
}
/*
* search forwards for the last contiguous page to transfer
*/
failed = 0;
for (i = 0; i < count; i++) {
if( failed || (reqaddr[i] != reqaddr[0] + i*btodb(NBPG)) ||
(reqaddr[i] / dmmax) != (reqaddr[0] / dmmax) ||
(rtvals[i] != VM_PAGER_OK)) {
failed = 1;
if( rtvals[i] == VM_PAGER_OK)
rtvals[i] = VM_PAGER_TRYAGAIN;
}
}
for(i = 0; i < count; i++) {
if( rtvals[i] != VM_PAGER_OK) {
if( swb[i])
--swb[i]->swb_locked;
}
}
for(i = 0; i < count; i++)
if( rtvals[i] != VM_PAGER_OK)
break;
if( i == 0) {
return VM_PAGER_TRYAGAIN;
}
count = i;
for(i=0;i<count;i++) {
if( reqaddr[i] == SWB_EMPTY)
printf("I/O to empty block????\n");
}
/*
*/
/*
* For synchronous writes, we clean up
* all completed async pageouts.
*/
if ((flags & B_ASYNC) == 0) {
swap_pager_clean();
}
kva = 0;
/*
* we allocate a new kva for transfers > 1 page
* but for transfers == 1 page, the swap_pager_free list contains
* entries that have pre-allocated kva's (for efficiency).
*/
if ( count > 1) {
kva = kmem_alloc_pageable(pager_map, count*NBPG);
if( !kva) {
for (i = 0; i < count; i++) {
if( swb[i])
--swb[i]->swb_locked;
rtvals[i] = VM_PAGER_TRYAGAIN;
}
return VM_PAGER_TRYAGAIN;
}
}
/*
* get a swap pager clean data structure, block until we get it
*/
if (queue_empty(&swap_pager_free)) {
/*
if (flags & B_ASYNC) {
for(i=0;i<count;i++) {
rtvals[i] = VM_PAGER_TRYAGAIN;
if( swb[i])
--swb[i]->swb_locked;
}
return VM_PAGER_TRYAGAIN;
}
*/
s = splbio();
if( curproc == pageproc)
(void) swap_pager_clean();
else
wakeup((caddr_t) &vm_pages_needed);
while (queue_empty(&swap_pager_free)) {
swap_pager_needflags |= SWAP_FREE_NEEDED;
tsleep((caddr_t)&swap_pager_free,
PVM, "swpfre", 0);
if( curproc == pageproc)
(void) swap_pager_clean();
else
wakeup((caddr_t) &vm_pages_needed);
}
splx(s);
}
queue_remove_first(&swap_pager_free, spc, swp_clean_t, spc_list);
if( !kva) {
kva = spc->spc_kva;
spc->spc_altkva = 0;
} else {
spc->spc_altkva = kva;
}
/*
* map our page(s) into kva for I/O
*/
for (i = 0; i < count; i++) {
pmap_kenter( kva + NBPG * i, VM_PAGE_TO_PHYS(m[i]));
}
pmap_update();
/*
* get the base I/O offset into the swap file
*/
for(i=0;i<count;i++) {
foff = m[i]->offset + paging_offset;
off = swap_pager_block_offset(swp, foff);
/*
* if we are setting the valid bit anew,
* then diminish the swap free space
*/
if( (swb[i]->swb_valid & (1 << off)) == 0)
vm_swap_size -= btodb(NBPG);
/*
* set the valid bit
*/
swb[i]->swb_valid |= (1 << off);
/*
* and unlock the data structure
*/
--swb[i]->swb_locked;
}
s = splbio();
/*
* Get a swap buffer header and perform the IO
*/
bp = spc->spc_bp;
bzero(bp, sizeof *bp);
bp->b_spc = spc;
bp->b_flags = B_BUSY;
bp->b_proc = &proc0; /* XXX (but without B_PHYS set this is ok) */
bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
bp->b_un.b_addr = (caddr_t) kva;
bp->b_blkno = reqaddr[0];
VHOLD(swapdev_vp);
bp->b_vp = swapdev_vp;
if (swapdev_vp->v_type == VBLK)
bp->b_dev = swapdev_vp->v_rdev;
bp->b_bcount = NBPG*count;
bp->b_bufsize = NBPG*count;
swapdev_vp->v_numoutput++;
/*
* If this is an async write we set up additional buffer fields
* and place a "cleaning" entry on the inuse queue.
*/
if ( flags & B_ASYNC ) {
spc->spc_flags = 0;
spc->spc_swp = swp;
for(i=0;i<count;i++)
spc->spc_m[i] = m[i];
spc->spc_count = count;
/*
* the completion routine for async writes
*/
bp->b_flags |= B_CALL;
bp->b_iodone = swap_pager_iodone;
bp->b_dirtyoff = 0;
bp->b_dirtyend = bp->b_bcount;
swp->sw_poip++;
queue_enter(&swap_pager_inuse, spc, swp_clean_t, spc_list);
} else {
swp->sw_poip++;
bp->b_flags |= B_CALL;
bp->b_iodone = swap_pager_iodone1;
}
/*
* perform the I/O
*/
VOP_STRATEGY(bp);
if ((flags & (B_READ|B_ASYNC)) == B_ASYNC ) {
if ((bp->b_flags & B_DONE) == B_DONE) {
swap_pager_clean();
}
splx(s);
for(i=0;i<count;i++) {
rtvals[i] = VM_PAGER_PEND;
}
return VM_PAGER_PEND;
}
/*
* wait for the sync I/O to complete
*/
while ((bp->b_flags & B_DONE) == 0) {
tsleep((caddr_t)bp, PVM, "swwrt", 0);
}
rv = (bp->b_flags & B_ERROR) ? VM_PAGER_FAIL : VM_PAGER_OK;
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_DIRTY|B_CALL|B_DONE);
--swp->sw_poip;
if (swp->sw_poip == 0)
wakeup((caddr_t) swp);
if (bp->b_vp)
brelvp(bp);
splx(s);
/*
* remove the mapping for kernel virtual
*/
pmap_remove(vm_map_pmap(pager_map), kva, kva + count * NBPG);
/*
* if we have written the page, then indicate that the page
* is clean.
*/
if (rv == VM_PAGER_OK) {
for(i=0;i<count;i++) {
if( rtvals[i] == VM_PAGER_OK) {
m[i]->flags |= PG_CLEAN;
m[i]->flags &= ~PG_LAUNDRY;
pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
/*
* optimization, if a page has been read during the
* pageout process, we activate it.
*/
if ( (m[i]->flags & PG_ACTIVE) == 0 &&
pmap_is_referenced(VM_PAGE_TO_PHYS(m[i])))
vm_page_activate(m[i]);
}
}
} else {
for(i=0;i<count;i++) {
rtvals[i] = rv;
m[i]->flags |= PG_LAUNDRY;
}
}
if( spc->spc_altkva)
kmem_free_wakeup(pager_map, kva, count * NBPG);
queue_enter(&swap_pager_free, spc, swp_clean_t, spc_list);
if (swap_pager_needflags & SWAP_FREE_NEEDED) {
swap_pager_needflags &= ~SWAP_FREE_NEEDED;
wakeup((caddr_t)&swap_pager_free);
}
return(rv);
}
boolean_t
swap_pager_clean()
{
register swp_clean_t spc, tspc;
register int s;
tspc = NULL;
if (queue_empty(&swap_pager_done))
return FALSE;
for (;;) {
s = splbio();
/*
* Look up and removal from done list must be done
* at splbio() to avoid conflicts with swap_pager_iodone.
*/
spc = (swp_clean_t) queue_first(&swap_pager_done);
while (!queue_end(&swap_pager_done, (queue_entry_t)spc)) {
if( spc->spc_altkva) {
pmap_remove(vm_map_pmap(pager_map), spc->spc_altkva, spc->spc_altkva + spc->spc_count * NBPG);
kmem_free_wakeup(pager_map, spc->spc_altkva, spc->spc_count * NBPG);
spc->spc_altkva = 0;
} else {
pmap_remove(vm_map_pmap(pager_map), spc->spc_kva, spc->spc_kva + NBPG);
}
swap_pager_finish(spc);
queue_remove(&swap_pager_done, spc, swp_clean_t, spc_list);
goto doclean;
}
/*
* No operations done, thats all we can do for now.
*/
splx(s);
break;
/*
* The desired page was found to be busy earlier in
* the scan but has since completed.
*/
doclean:
if (tspc && tspc == spc) {
tspc = NULL;
}
spc->spc_flags = 0;
queue_enter(&swap_pager_free, spc, swp_clean_t, spc_list);
if (swap_pager_needflags & SWAP_FREE_NEEDED) {
swap_pager_needflags &= ~SWAP_FREE_NEEDED;
wakeup((caddr_t)&swap_pager_free);
}
++cleandone;
splx(s);
}
return(tspc ? TRUE : FALSE);
}
void
swap_pager_finish(spc)
register swp_clean_t spc;
{
vm_object_t object = spc->spc_m[0]->object;
int i;
if ((object->paging_in_progress -= spc->spc_count) == 0)
thread_wakeup((int) object);
/*
* If no error mark as clean and inform the pmap system.
* If error, mark as dirty so we will try again.
* (XXX could get stuck doing this, should give up after awhile)
*/
if (spc->spc_flags & SPC_ERROR) {
for(i=0;i<spc->spc_count;i++) {
printf("swap_pager_finish: clean of page %x failed\n",
VM_PAGE_TO_PHYS(spc->spc_m[i]));
spc->spc_m[i]->flags |= PG_LAUNDRY;
}
} else {
for(i=0;i<spc->spc_count;i++) {
pmap_clear_modify(VM_PAGE_TO_PHYS(spc->spc_m[i]));
spc->spc_m[i]->flags |= PG_CLEAN;
}
}
for(i=0;i<spc->spc_count;i++) {
/*
* we wakeup any processes that are waiting on
* these pages.
*/
PAGE_WAKEUP(spc->spc_m[i]);
}
nswiodone -= spc->spc_count;
return;
}
/*
* swap_pager_iodone
*/
void
swap_pager_iodone(bp)
register struct buf *bp;
{
register swp_clean_t spc;
int s;
s = splbio();
spc = (swp_clean_t) bp->b_spc;
queue_remove(&swap_pager_inuse, spc, swp_clean_t, spc_list);
queue_enter(&swap_pager_done, spc, swp_clean_t, spc_list);
if (bp->b_flags & B_ERROR) {
spc->spc_flags |= SPC_ERROR;
printf("error %d blkno %d sz %d ",
bp->b_error, bp->b_blkno, bp->b_bcount);
}
/*
if ((bp->b_flags & B_READ) == 0)
vwakeup(bp);
*/
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_DIRTY|B_ASYNC);
if (bp->b_vp) {
brelvp(bp);
}
nswiodone += spc->spc_count;
if (--spc->spc_swp->sw_poip == 0) {
wakeup((caddr_t)spc->spc_swp);
}
if ((swap_pager_needflags & SWAP_FREE_NEEDED) ||
queue_empty(&swap_pager_inuse)) {
swap_pager_needflags &= ~SWAP_FREE_NEEDED;
wakeup((caddr_t)&swap_pager_free);
wakeup((caddr_t)&vm_pages_needed);
}
if (vm_pageout_pages_needed) {
wakeup((caddr_t)&vm_pageout_pages_needed);
}
if (queue_empty(&swap_pager_inuse) ||
(vm_page_free_count < vm_page_free_min &&
nswiodone + vm_page_free_count >= vm_page_free_min) ) {
wakeup((caddr_t)&vm_pages_needed);
}
splx(s);
}
/*
* allocate a physical buffer
*/
struct buf *
getpbuf() {
int s;
struct buf *bp;
s = splbio();
/* get a bp from the swap buffer header pool */
while (bswlist.av_forw == NULL) {
bswlist.b_flags |= B_WANTED;
tsleep((caddr_t)&bswlist, PVM, "wswbuf", 0);
}
bp = bswlist.av_forw;
bswlist.av_forw = bp->av_forw;
splx(s);
bzero(bp, sizeof *bp);
return bp;
}
/*
* allocate a physical buffer, if one is available
*/
struct buf *
trypbuf() {
int s;
struct buf *bp;
s = splbio();
if( bswlist.av_forw == NULL) {
splx(s);
return NULL;
}
bp = bswlist.av_forw;
bswlist.av_forw = bp->av_forw;
splx(s);
bzero(bp, sizeof *bp);
return bp;
}
/*
* release a physical buffer
*/
void
relpbuf(bp)
struct buf *bp;
{
int s;
s = splbio();
bp->av_forw = bswlist.av_forw;
bswlist.av_forw = bp;
if (bswlist.b_flags & B_WANTED) {
bswlist.b_flags &= ~B_WANTED;
wakeup((caddr_t)&bswlist);
}
splx(s);
}
/*
* return true if any swap control structures can be allocated
*/
int
swap_pager_ready() {
if( !queue_empty( &swap_pager_free))
return 1;
else
return 0;
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.