1025 lines
23 KiB
C
1025 lines
23 KiB
C
/* $NetBSD: uvm_pdaemon.c,v 1.109 2017/10/28 00:37:13 pgoyette Exp $ */
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/*
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* Copyright (c) 1997 Charles D. Cranor and Washington University.
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* Copyright (c) 1991, 1993, The Regents of the University of California.
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*
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94
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* from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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/*
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* uvm_pdaemon.c: the page daemon
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.109 2017/10/28 00:37:13 pgoyette Exp $");
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#include "opt_uvmhist.h"
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#include "opt_readahead.h"
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#include <sys/param.h>
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#include <sys/proc.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/pool.h>
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#include <sys/buf.h>
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#include <sys/module.h>
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#include <sys/atomic.h>
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#include <uvm/uvm.h>
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#include <uvm/uvm_pdpolicy.h>
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#ifdef UVMHIST
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UVMHIST_DEFINE(pdhist);
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#endif
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/*
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* UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate
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* in a pass thru the inactive list when swap is full. the value should be
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* "small"... if it's too large we'll cycle the active pages thru the inactive
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* queue too quickly to for them to be referenced and avoid being freed.
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*/
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#define UVMPD_NUMDIRTYREACTS 16
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#define UVMPD_NUMTRYLOCKOWNER 16
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/*
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* local prototypes
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*/
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static void uvmpd_scan(void);
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static void uvmpd_scan_queue(void);
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static void uvmpd_tune(void);
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static unsigned int uvm_pagedaemon_waiters;
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/*
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* XXX hack to avoid hangs when large processes fork.
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*/
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u_int uvm_extrapages;
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/*
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* uvm_wait: wait (sleep) for the page daemon to free some pages
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*
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* => should be called with all locks released
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* => should _not_ be called by the page daemon (to avoid deadlock)
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*/
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void
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uvm_wait(const char *wmsg)
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{
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int timo = 0;
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mutex_spin_enter(&uvm_fpageqlock);
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/*
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* check for page daemon going to sleep (waiting for itself)
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*/
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if (curlwp == uvm.pagedaemon_lwp && uvmexp.paging == 0) {
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/*
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* now we have a problem: the pagedaemon wants to go to
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* sleep until it frees more memory. but how can it
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* free more memory if it is asleep? that is a deadlock.
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* we have two options:
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* [1] panic now
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* [2] put a timeout on the sleep, thus causing the
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* pagedaemon to only pause (rather than sleep forever)
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*
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* note that option [2] will only help us if we get lucky
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* and some other process on the system breaks the deadlock
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* by exiting or freeing memory (thus allowing the pagedaemon
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* to continue). for now we panic if DEBUG is defined,
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* otherwise we hope for the best with option [2] (better
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* yet, this should never happen in the first place!).
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*/
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printf("pagedaemon: deadlock detected!\n");
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timo = hz >> 3; /* set timeout */
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#if defined(DEBUG)
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/* DEBUG: panic so we can debug it */
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panic("pagedaemon deadlock");
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#endif
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}
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uvm_pagedaemon_waiters++;
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wakeup(&uvm.pagedaemon); /* wake the daemon! */
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UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm_fpageqlock, false, wmsg, timo);
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}
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/*
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* uvm_kick_pdaemon: perform checks to determine if we need to
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* give the pagedaemon a nudge, and do so if necessary.
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*
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* => called with uvm_fpageqlock held.
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*/
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void
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uvm_kick_pdaemon(void)
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{
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KASSERT(mutex_owned(&uvm_fpageqlock));
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if (uvmexp.free + uvmexp.paging < uvmexp.freemin ||
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(uvmexp.free + uvmexp.paging < uvmexp.freetarg &&
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uvmpdpol_needsscan_p()) ||
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uvm_km_va_starved_p()) {
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wakeup(&uvm.pagedaemon);
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}
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}
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/*
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* uvmpd_tune: tune paging parameters
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*
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* => called when ever memory is added (or removed?) to the system
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* => caller must call with page queues locked
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*/
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static void
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uvmpd_tune(void)
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{
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int val;
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UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist);
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/*
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* try to keep 0.5% of available RAM free, but limit to between
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* 128k and 1024k per-CPU. XXX: what are these values good for?
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*/
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val = uvmexp.npages / 200;
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val = MAX(val, (128*1024) >> PAGE_SHIFT);
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val = MIN(val, (1024*1024) >> PAGE_SHIFT);
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val *= ncpu;
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/* Make sure there's always a user page free. */
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if (val < uvmexp.reserve_kernel + 1)
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val = uvmexp.reserve_kernel + 1;
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uvmexp.freemin = val;
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/* Calculate free target. */
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val = (uvmexp.freemin * 4) / 3;
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if (val <= uvmexp.freemin)
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val = uvmexp.freemin + 1;
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uvmexp.freetarg = val + atomic_swap_uint(&uvm_extrapages, 0);
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uvmexp.wiredmax = uvmexp.npages / 3;
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UVMHIST_LOG(pdhist, "<- done, freemin=%jd, freetarg=%jd, wiredmax=%jd",
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uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0);
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}
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/*
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* uvm_pageout: the main loop for the pagedaemon
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*/
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void
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uvm_pageout(void *arg)
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{
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int bufcnt, npages = 0;
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int extrapages = 0;
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struct pool *pp;
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UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist);
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UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0);
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/*
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* ensure correct priority and set paging parameters...
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*/
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uvm.pagedaemon_lwp = curlwp;
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mutex_enter(&uvm_pageqlock);
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npages = uvmexp.npages;
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uvmpd_tune();
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mutex_exit(&uvm_pageqlock);
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/*
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* main loop
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*/
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for (;;) {
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bool needsscan, needsfree, kmem_va_starved;
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kmem_va_starved = uvm_km_va_starved_p();
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mutex_spin_enter(&uvm_fpageqlock);
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if ((uvm_pagedaemon_waiters == 0 || uvmexp.paging > 0) &&
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!kmem_va_starved) {
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UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0);
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UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon,
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&uvm_fpageqlock, false, "pgdaemon", 0);
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uvmexp.pdwoke++;
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UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0);
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} else {
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mutex_spin_exit(&uvm_fpageqlock);
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}
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/*
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* now lock page queues and recompute inactive count
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*/
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mutex_enter(&uvm_pageqlock);
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if (npages != uvmexp.npages || extrapages != uvm_extrapages) {
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npages = uvmexp.npages;
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extrapages = uvm_extrapages;
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mutex_spin_enter(&uvm_fpageqlock);
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uvmpd_tune();
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mutex_spin_exit(&uvm_fpageqlock);
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}
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uvmpdpol_tune();
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/*
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* Estimate a hint. Note that bufmem are returned to
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* system only when entire pool page is empty.
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*/
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mutex_spin_enter(&uvm_fpageqlock);
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bufcnt = uvmexp.freetarg - uvmexp.free;
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if (bufcnt < 0)
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bufcnt = 0;
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UVMHIST_LOG(pdhist," free/ftarg=%jd/%jd",
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uvmexp.free, uvmexp.freetarg, 0,0);
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needsfree = uvmexp.free + uvmexp.paging < uvmexp.freetarg;
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needsscan = needsfree || uvmpdpol_needsscan_p();
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/*
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* scan if needed
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*/
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if (needsscan) {
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mutex_spin_exit(&uvm_fpageqlock);
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uvmpd_scan();
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mutex_spin_enter(&uvm_fpageqlock);
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}
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/*
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* if there's any free memory to be had,
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* wake up any waiters.
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*/
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if (uvmexp.free > uvmexp.reserve_kernel ||
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uvmexp.paging == 0) {
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wakeup(&uvmexp.free);
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uvm_pagedaemon_waiters = 0;
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}
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mutex_spin_exit(&uvm_fpageqlock);
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/*
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* scan done. unlock page queues (the only lock we are holding)
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*/
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mutex_exit(&uvm_pageqlock);
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/*
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* if we don't need free memory, we're done.
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*/
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if (!needsfree && !kmem_va_starved)
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continue;
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/*
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* kill unused metadata buffers.
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*/
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mutex_enter(&bufcache_lock);
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buf_drain(bufcnt << PAGE_SHIFT);
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mutex_exit(&bufcache_lock);
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/*
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* drain the pools.
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*/
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pool_drain(&pp);
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}
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/*NOTREACHED*/
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}
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/*
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* uvm_aiodone_worker: a workqueue callback for the aiodone daemon.
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*/
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void
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uvm_aiodone_worker(struct work *wk, void *dummy)
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{
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struct buf *bp = (void *)wk;
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KASSERT(&bp->b_work == wk);
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/*
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* process an i/o that's done.
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*/
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(*bp->b_iodone)(bp);
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}
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void
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uvm_pageout_start(int npages)
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{
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mutex_spin_enter(&uvm_fpageqlock);
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uvmexp.paging += npages;
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mutex_spin_exit(&uvm_fpageqlock);
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}
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void
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uvm_pageout_done(int npages)
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{
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mutex_spin_enter(&uvm_fpageqlock);
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KASSERT(uvmexp.paging >= npages);
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uvmexp.paging -= npages;
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/*
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* wake up either of pagedaemon or LWPs waiting for it.
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*/
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if (uvmexp.free <= uvmexp.reserve_kernel) {
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wakeup(&uvm.pagedaemon);
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} else {
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wakeup(&uvmexp.free);
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uvm_pagedaemon_waiters = 0;
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}
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mutex_spin_exit(&uvm_fpageqlock);
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}
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/*
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* uvmpd_trylockowner: trylock the page's owner.
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*
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* => called with pageq locked.
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* => resolve orphaned O->A loaned page.
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* => return the locked mutex on success. otherwise, return NULL.
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*/
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kmutex_t *
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uvmpd_trylockowner(struct vm_page *pg)
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{
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struct uvm_object *uobj = pg->uobject;
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kmutex_t *slock;
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KASSERT(mutex_owned(&uvm_pageqlock));
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if (uobj != NULL) {
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slock = uobj->vmobjlock;
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} else {
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struct vm_anon *anon = pg->uanon;
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KASSERT(anon != NULL);
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slock = anon->an_lock;
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}
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if (!mutex_tryenter(slock)) {
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return NULL;
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}
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if (uobj == NULL) {
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/*
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* set PQ_ANON if it isn't set already.
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*/
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if ((pg->pqflags & PQ_ANON) == 0) {
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KASSERT(pg->loan_count > 0);
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pg->loan_count--;
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pg->pqflags |= PQ_ANON;
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/* anon now owns it */
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}
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}
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return slock;
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}
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#if defined(VMSWAP)
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struct swapcluster {
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int swc_slot;
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int swc_nallocated;
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int swc_nused;
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struct vm_page *swc_pages[howmany(MAXPHYS, MIN_PAGE_SIZE)];
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};
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static void
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swapcluster_init(struct swapcluster *swc)
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{
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swc->swc_slot = 0;
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swc->swc_nused = 0;
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}
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static int
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swapcluster_allocslots(struct swapcluster *swc)
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{
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int slot;
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int npages;
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if (swc->swc_slot != 0) {
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return 0;
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}
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/* Even with strange MAXPHYS, the shift
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implicitly rounds down to a page. */
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npages = MAXPHYS >> PAGE_SHIFT;
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slot = uvm_swap_alloc(&npages, true);
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if (slot == 0) {
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return ENOMEM;
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}
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swc->swc_slot = slot;
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swc->swc_nallocated = npages;
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swc->swc_nused = 0;
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return 0;
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}
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static int
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swapcluster_add(struct swapcluster *swc, struct vm_page *pg)
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{
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int slot;
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struct uvm_object *uobj;
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KASSERT(swc->swc_slot != 0);
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KASSERT(swc->swc_nused < swc->swc_nallocated);
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KASSERT((pg->pqflags & PQ_SWAPBACKED) != 0);
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slot = swc->swc_slot + swc->swc_nused;
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uobj = pg->uobject;
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if (uobj == NULL) {
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KASSERT(mutex_owned(pg->uanon->an_lock));
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pg->uanon->an_swslot = slot;
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} else {
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int result;
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KASSERT(mutex_owned(uobj->vmobjlock));
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result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot);
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if (result == -1) {
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return ENOMEM;
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}
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}
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swc->swc_pages[swc->swc_nused] = pg;
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swc->swc_nused++;
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return 0;
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}
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static void
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swapcluster_flush(struct swapcluster *swc, bool now)
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{
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int slot;
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int nused;
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int nallocated;
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int error __diagused;
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if (swc->swc_slot == 0) {
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return;
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}
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KASSERT(swc->swc_nused <= swc->swc_nallocated);
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slot = swc->swc_slot;
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nused = swc->swc_nused;
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nallocated = swc->swc_nallocated;
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/*
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* if this is the final pageout we could have a few
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* unused swap blocks. if so, free them now.
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*/
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if (nused < nallocated) {
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if (!now) {
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return;
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}
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|
uvm_swap_free(slot + nused, nallocated - nused);
|
|
}
|
|
|
|
/*
|
|
* now start the pageout.
|
|
*/
|
|
|
|
if (nused > 0) {
|
|
uvmexp.pdpageouts++;
|
|
uvm_pageout_start(nused);
|
|
error = uvm_swap_put(slot, swc->swc_pages, nused, 0);
|
|
KASSERT(error == 0 || error == ENOMEM);
|
|
}
|
|
|
|
/*
|
|
* zero swslot to indicate that we are
|
|
* no longer building a swap-backed cluster.
|
|
*/
|
|
|
|
swc->swc_slot = 0;
|
|
swc->swc_nused = 0;
|
|
}
|
|
|
|
static int
|
|
swapcluster_nused(struct swapcluster *swc)
|
|
{
|
|
|
|
return swc->swc_nused;
|
|
}
|
|
|
|
/*
|
|
* uvmpd_dropswap: free any swap allocated to this page.
|
|
*
|
|
* => called with owner locked.
|
|
* => return true if a page had an associated slot.
|
|
*/
|
|
|
|
static bool
|
|
uvmpd_dropswap(struct vm_page *pg)
|
|
{
|
|
bool result = false;
|
|
struct vm_anon *anon = pg->uanon;
|
|
|
|
if ((pg->pqflags & PQ_ANON) && anon->an_swslot) {
|
|
uvm_swap_free(anon->an_swslot, 1);
|
|
anon->an_swslot = 0;
|
|
pg->flags &= ~PG_CLEAN;
|
|
result = true;
|
|
} else if (pg->pqflags & PQ_AOBJ) {
|
|
int slot = uao_set_swslot(pg->uobject,
|
|
pg->offset >> PAGE_SHIFT, 0);
|
|
if (slot) {
|
|
uvm_swap_free(slot, 1);
|
|
pg->flags &= ~PG_CLEAN;
|
|
result = true;
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* uvmpd_trydropswap: try to free any swap allocated to this page.
|
|
*
|
|
* => return true if a slot is successfully freed.
|
|
*/
|
|
|
|
bool
|
|
uvmpd_trydropswap(struct vm_page *pg)
|
|
{
|
|
kmutex_t *slock;
|
|
bool result;
|
|
|
|
if ((pg->flags & PG_BUSY) != 0) {
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* lock the page's owner.
|
|
*/
|
|
|
|
slock = uvmpd_trylockowner(pg);
|
|
if (slock == NULL) {
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* skip this page if it's busy.
|
|
*/
|
|
|
|
if ((pg->flags & PG_BUSY) != 0) {
|
|
mutex_exit(slock);
|
|
return false;
|
|
}
|
|
|
|
result = uvmpd_dropswap(pg);
|
|
|
|
mutex_exit(slock);
|
|
|
|
return result;
|
|
}
|
|
|
|
#endif /* defined(VMSWAP) */
|
|
|
|
/*
|
|
* uvmpd_scan_queue: scan an replace candidate list for pages
|
|
* to clean or free.
|
|
*
|
|
* => called with page queues locked
|
|
* => we work on meeting our free target by converting inactive pages
|
|
* into free pages.
|
|
* => we handle the building of swap-backed clusters
|
|
*/
|
|
|
|
static void
|
|
uvmpd_scan_queue(void)
|
|
{
|
|
struct vm_page *p;
|
|
struct uvm_object *uobj;
|
|
struct vm_anon *anon;
|
|
#if defined(VMSWAP)
|
|
struct swapcluster swc;
|
|
#endif /* defined(VMSWAP) */
|
|
int dirtyreacts;
|
|
int lockownerfail;
|
|
kmutex_t *slock;
|
|
UVMHIST_FUNC("uvmpd_scan_queue"); UVMHIST_CALLED(pdhist);
|
|
|
|
/*
|
|
* swslot is non-zero if we are building a swap cluster. we want
|
|
* to stay in the loop while we have a page to scan or we have
|
|
* a swap-cluster to build.
|
|
*/
|
|
|
|
#if defined(VMSWAP)
|
|
swapcluster_init(&swc);
|
|
#endif /* defined(VMSWAP) */
|
|
|
|
dirtyreacts = 0;
|
|
lockownerfail = 0;
|
|
uvmpdpol_scaninit();
|
|
|
|
while (/* CONSTCOND */ 1) {
|
|
|
|
/*
|
|
* see if we've met the free target.
|
|
*/
|
|
|
|
if (uvmexp.free + uvmexp.paging
|
|
#if defined(VMSWAP)
|
|
+ swapcluster_nused(&swc)
|
|
#endif /* defined(VMSWAP) */
|
|
>= uvmexp.freetarg << 2 ||
|
|
dirtyreacts == UVMPD_NUMDIRTYREACTS) {
|
|
UVMHIST_LOG(pdhist," met free target: "
|
|
"exit loop", 0, 0, 0, 0);
|
|
break;
|
|
}
|
|
|
|
p = uvmpdpol_selectvictim();
|
|
if (p == NULL) {
|
|
break;
|
|
}
|
|
KASSERT(uvmpdpol_pageisqueued_p(p));
|
|
KASSERT(p->wire_count == 0);
|
|
|
|
/*
|
|
* we are below target and have a new page to consider.
|
|
*/
|
|
|
|
anon = p->uanon;
|
|
uobj = p->uobject;
|
|
|
|
/*
|
|
* first we attempt to lock the object that this page
|
|
* belongs to. if our attempt fails we skip on to
|
|
* the next page (no harm done). it is important to
|
|
* "try" locking the object as we are locking in the
|
|
* wrong order (pageq -> object) and we don't want to
|
|
* deadlock.
|
|
*
|
|
* the only time we expect to see an ownerless page
|
|
* (i.e. a page with no uobject and !PQ_ANON) is if an
|
|
* anon has loaned a page from a uvm_object and the
|
|
* uvm_object has dropped the ownership. in that
|
|
* case, the anon can "take over" the loaned page
|
|
* and make it its own.
|
|
*/
|
|
|
|
slock = uvmpd_trylockowner(p);
|
|
if (slock == NULL) {
|
|
/*
|
|
* yield cpu to make a chance for an LWP holding
|
|
* the lock run. otherwise we can busy-loop too long
|
|
* if the page queue is filled with a lot of pages
|
|
* from few objects.
|
|
*/
|
|
lockownerfail++;
|
|
if (lockownerfail > UVMPD_NUMTRYLOCKOWNER) {
|
|
mutex_exit(&uvm_pageqlock);
|
|
/* XXX Better than yielding but inadequate. */
|
|
kpause("livelock", false, 1, NULL);
|
|
mutex_enter(&uvm_pageqlock);
|
|
lockownerfail = 0;
|
|
}
|
|
continue;
|
|
}
|
|
if (p->flags & PG_BUSY) {
|
|
mutex_exit(slock);
|
|
uvmexp.pdbusy++;
|
|
continue;
|
|
}
|
|
|
|
/* does the page belong to an object? */
|
|
if (uobj != NULL) {
|
|
uvmexp.pdobscan++;
|
|
} else {
|
|
#if defined(VMSWAP)
|
|
KASSERT(anon != NULL);
|
|
uvmexp.pdanscan++;
|
|
#else /* defined(VMSWAP) */
|
|
panic("%s: anon", __func__);
|
|
#endif /* defined(VMSWAP) */
|
|
}
|
|
|
|
|
|
/*
|
|
* we now have the object and the page queues locked.
|
|
* if the page is not swap-backed, call the object's
|
|
* pager to flush and free the page.
|
|
*/
|
|
|
|
#if defined(READAHEAD_STATS)
|
|
if ((p->pqflags & PQ_READAHEAD) != 0) {
|
|
p->pqflags &= ~PQ_READAHEAD;
|
|
uvm_ra_miss.ev_count++;
|
|
}
|
|
#endif /* defined(READAHEAD_STATS) */
|
|
|
|
if ((p->pqflags & PQ_SWAPBACKED) == 0) {
|
|
KASSERT(uobj != NULL);
|
|
mutex_exit(&uvm_pageqlock);
|
|
(void) (uobj->pgops->pgo_put)(uobj, p->offset,
|
|
p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE);
|
|
mutex_enter(&uvm_pageqlock);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* the page is swap-backed. remove all the permissions
|
|
* from the page so we can sync the modified info
|
|
* without any race conditions. if the page is clean
|
|
* we can free it now and continue.
|
|
*/
|
|
|
|
pmap_page_protect(p, VM_PROT_NONE);
|
|
if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) {
|
|
p->flags &= ~(PG_CLEAN);
|
|
}
|
|
if (p->flags & PG_CLEAN) {
|
|
int slot;
|
|
int pageidx;
|
|
|
|
pageidx = p->offset >> PAGE_SHIFT;
|
|
uvm_pagefree(p);
|
|
uvmexp.pdfreed++;
|
|
|
|
/*
|
|
* for anons, we need to remove the page
|
|
* from the anon ourselves. for aobjs,
|
|
* pagefree did that for us.
|
|
*/
|
|
|
|
if (anon) {
|
|
KASSERT(anon->an_swslot != 0);
|
|
anon->an_page = NULL;
|
|
slot = anon->an_swslot;
|
|
} else {
|
|
slot = uao_find_swslot(uobj, pageidx);
|
|
}
|
|
mutex_exit(slock);
|
|
|
|
if (slot > 0) {
|
|
/* this page is now only in swap. */
|
|
mutex_enter(&uvm_swap_data_lock);
|
|
KASSERT(uvmexp.swpgonly < uvmexp.swpginuse);
|
|
uvmexp.swpgonly++;
|
|
mutex_exit(&uvm_swap_data_lock);
|
|
}
|
|
continue;
|
|
}
|
|
|
|
#if defined(VMSWAP)
|
|
/*
|
|
* this page is dirty, skip it if we'll have met our
|
|
* free target when all the current pageouts complete.
|
|
*/
|
|
|
|
if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) {
|
|
mutex_exit(slock);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* free any swap space allocated to the page since
|
|
* we'll have to write it again with its new data.
|
|
*/
|
|
|
|
uvmpd_dropswap(p);
|
|
|
|
/*
|
|
* start new swap pageout cluster (if necessary).
|
|
*
|
|
* if swap is full reactivate this page so that
|
|
* we eventually cycle all pages through the
|
|
* inactive queue.
|
|
*/
|
|
|
|
if (swapcluster_allocslots(&swc)) {
|
|
dirtyreacts++;
|
|
uvm_pageactivate(p);
|
|
mutex_exit(slock);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* at this point, we're definitely going reuse this
|
|
* page. mark the page busy and delayed-free.
|
|
* we should remove the page from the page queues
|
|
* so we don't ever look at it again.
|
|
* adjust counters and such.
|
|
*/
|
|
|
|
p->flags |= PG_BUSY;
|
|
UVM_PAGE_OWN(p, "scan_queue");
|
|
|
|
p->flags |= PG_PAGEOUT;
|
|
uvm_pagedequeue(p);
|
|
|
|
uvmexp.pgswapout++;
|
|
mutex_exit(&uvm_pageqlock);
|
|
|
|
/*
|
|
* add the new page to the cluster.
|
|
*/
|
|
|
|
if (swapcluster_add(&swc, p)) {
|
|
p->flags &= ~(PG_BUSY|PG_PAGEOUT);
|
|
UVM_PAGE_OWN(p, NULL);
|
|
mutex_enter(&uvm_pageqlock);
|
|
dirtyreacts++;
|
|
uvm_pageactivate(p);
|
|
mutex_exit(slock);
|
|
continue;
|
|
}
|
|
mutex_exit(slock);
|
|
|
|
swapcluster_flush(&swc, false);
|
|
mutex_enter(&uvm_pageqlock);
|
|
|
|
/*
|
|
* the pageout is in progress. bump counters and set up
|
|
* for the next loop.
|
|
*/
|
|
|
|
uvmexp.pdpending++;
|
|
|
|
#else /* defined(VMSWAP) */
|
|
uvm_pageactivate(p);
|
|
mutex_exit(slock);
|
|
#endif /* defined(VMSWAP) */
|
|
}
|
|
|
|
#if defined(VMSWAP)
|
|
mutex_exit(&uvm_pageqlock);
|
|
swapcluster_flush(&swc, true);
|
|
mutex_enter(&uvm_pageqlock);
|
|
#endif /* defined(VMSWAP) */
|
|
}
|
|
|
|
/*
|
|
* uvmpd_scan: scan the page queues and attempt to meet our targets.
|
|
*
|
|
* => called with pageq's locked
|
|
*/
|
|
|
|
static void
|
|
uvmpd_scan(void)
|
|
{
|
|
int swap_shortage, pages_freed;
|
|
UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist);
|
|
|
|
uvmexp.pdrevs++;
|
|
|
|
/*
|
|
* work on meeting our targets. first we work on our free target
|
|
* by converting inactive pages into free pages. then we work on
|
|
* meeting our inactive target by converting active pages to
|
|
* inactive ones.
|
|
*/
|
|
|
|
UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0);
|
|
|
|
pages_freed = uvmexp.pdfreed;
|
|
uvmpd_scan_queue();
|
|
pages_freed = uvmexp.pdfreed - pages_freed;
|
|
|
|
/*
|
|
* detect if we're not going to be able to page anything out
|
|
* until we free some swap resources from active pages.
|
|
*/
|
|
|
|
swap_shortage = 0;
|
|
if (uvmexp.free < uvmexp.freetarg &&
|
|
uvmexp.swpginuse >= uvmexp.swpgavail &&
|
|
!uvm_swapisfull() &&
|
|
pages_freed == 0) {
|
|
swap_shortage = uvmexp.freetarg - uvmexp.free;
|
|
}
|
|
|
|
uvmpdpol_balancequeue(swap_shortage);
|
|
|
|
/*
|
|
* if still below the minimum target, try unloading kernel
|
|
* modules.
|
|
*/
|
|
|
|
if (uvmexp.free < uvmexp.freemin) {
|
|
module_thread_kick();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* uvm_reclaimable: decide whether to wait for pagedaemon.
|
|
*
|
|
* => return true if it seems to be worth to do uvm_wait.
|
|
*
|
|
* XXX should be tunable.
|
|
* XXX should consider pools, etc?
|
|
*/
|
|
|
|
bool
|
|
uvm_reclaimable(void)
|
|
{
|
|
int filepages;
|
|
int active, inactive;
|
|
|
|
/*
|
|
* if swap is not full, no problem.
|
|
*/
|
|
|
|
if (!uvm_swapisfull()) {
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* file-backed pages can be reclaimed even when swap is full.
|
|
* if we have more than 1/16 of pageable memory or 5MB, try to reclaim.
|
|
*
|
|
* XXX assume the worst case, ie. all wired pages are file-backed.
|
|
*
|
|
* XXX should consider about other reclaimable memory.
|
|
* XXX ie. pools, traditional buffer cache.
|
|
*/
|
|
|
|
filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired;
|
|
uvm_estimatepageable(&active, &inactive);
|
|
if (filepages >= MIN((active + inactive) >> 4,
|
|
5 * 1024 * 1024 >> PAGE_SHIFT)) {
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* kill the process, fail allocation, etc..
|
|
*/
|
|
|
|
return false;
|
|
}
|
|
|
|
void
|
|
uvm_estimatepageable(int *active, int *inactive)
|
|
{
|
|
|
|
uvmpdpol_estimatepageable(active, inactive);
|
|
}
|
|
|