freebsd-dev/sys/vm/vm_pageout.h
Alan Cox 56ce06907c The flag "vm_pages_needed" has long served two distinct purposes: (1) to
indicate that threads are waiting for free pages to become available and
(2) to indicate whether a wakeup call has been sent to the page daemon.
The trouble is that a single flag cannot really serve both purposes, because
we have two distinct targets for when to wakeup threads waiting for free
pages versus when the page daemon has completed its work.  In particular,
the flag will be cleared by vm_page_free() before the page daemon has met
its target, and this can lead to the OOM killer being invoked prematurely.
To address this problem, a new flag "vm_pageout_wanted" is introduced.

Discussed with:	jeff
Reviewed by:	kib, markj
Tested by:	markj
Sponsored by:	EMC / Isilon Storage Division
2016-05-27 19:15:45 +00:00

108 lines
3.6 KiB
C

/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* 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.
* 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: @(#)vm_pageout.h 8.2 (Berkeley) 1/12/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Author: Avadis Tevanian, Jr.
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $FreeBSD$
*/
#ifndef _VM_VM_PAGEOUT_H_
#define _VM_VM_PAGEOUT_H_
/*
* Header file for pageout daemon.
*/
/*
* Exported data structures.
*/
extern int vm_page_max_wired;
extern int vm_pageout_deficit;
extern int vm_pageout_page_count;
extern bool vm_pageout_wanted;
extern bool vm_pages_needed;
/*
* Swap out requests
*/
#define VM_SWAP_NORMAL 1
#define VM_SWAP_IDLE 2
#define VM_OOM_MEM 1
#define VM_OOM_SWAPZ 2
/*
* Exported routines.
*/
/*
* Signal pageout-daemon and wait for it.
*/
extern void pagedaemon_wakeup(void);
#define VM_WAIT vm_wait()
#define VM_WAITPFAULT vm_waitpfault()
extern void vm_wait(void);
extern void vm_waitpfault(void);
#ifdef _KERNEL
int vm_pageout_flush(vm_page_t *, int, int, int, int *, boolean_t *);
void vm_pageout_oom(int shortage);
#endif
#endif /* _VM_VM_PAGEOUT_H_ */