Historically we have not distinguished between kernel wirings and user wirings for accounting purposes. User wirings (via mlock(2)) were subject to a global limit on the number of wired pages, so if large swaths of physical memory were wired by the kernel, as happens with the ZFS ARC among other things, the limit could be exceeded, causing user wirings to fail. The change adds a new counter, v_user_wire_count, which counts the number of virtual pages wired by user processes via mlock(2) and mlockall(2). Only user-wired pages are subject to the system-wide limit which helps provide some safety against deadlocks. In particular, while sources of kernel wirings typically support some backpressure mechanism, there is no way to reclaim user-wired pages shorting of killing the wiring process. The limit is exported as vm.max_user_wired, renamed from vm.max_wired, and changed from u_int to u_long. The choice to count virtual user-wired pages rather than physical pages was done for simplicity. There are mechanisms that can cause user-wired mappings to be destroyed while maintaining a wiring of the backing physical page; these make it difficult to accurately track user wirings at the physical page layer. The change also closes some holes which allowed user wirings to succeed even when they would cause the system limit to be exceeded. For instance, mmap() may now fail with ENOMEM in a process that has called mlockall(MCL_FUTURE) if the new mapping would cause the user wiring limit to be exceeded. Note that bhyve -S is subject to the user wiring limit, which defaults to 1/3 of physical RAM. Users that wish to exceed the limit must tune vm.max_user_wired. Reviewed by: kib, ngie (mlock() test changes) Tested by: pho (earlier version) MFC after: 45 days Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D19908
239 lines
7.7 KiB
C
239 lines
7.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1993
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* The Regents of the University of California. All rights reserved.
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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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* @(#)vmmeter.h 8.2 (Berkeley) 7/10/94
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* $FreeBSD$
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*/
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#ifndef _SYS_VMMETER_H_
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#define _SYS_VMMETER_H_
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/*
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* This value is used by ps(1) to change sleep state flag from 'S' to
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* 'I' and by the sched process to set the alarm clock.
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*/
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#define MAXSLP 20
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struct vmtotal {
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uint64_t t_vm; /* total virtual memory */
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uint64_t t_avm; /* active virtual memory */
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uint64_t t_rm; /* total real memory in use */
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uint64_t t_arm; /* active real memory */
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uint64_t t_vmshr; /* shared virtual memory */
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uint64_t t_avmshr; /* active shared virtual memory */
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uint64_t t_rmshr; /* shared real memory */
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uint64_t t_armshr; /* active shared real memory */
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uint64_t t_free; /* free memory pages */
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int16_t t_rq; /* length of the run queue */
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int16_t t_dw; /* threads in ``disk wait'' (neg
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priority) */
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int16_t t_pw; /* threads in page wait */
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int16_t t_sl; /* threads sleeping in core */
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int16_t t_sw; /* swapped out runnable/short
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block threads */
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uint16_t t_pad[3];
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};
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#if defined(_KERNEL) || defined(_WANT_VMMETER)
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#include <sys/counter.h>
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#ifdef _KERNEL
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#define VMMETER_ALIGNED __aligned(CACHE_LINE_SIZE)
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#else
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#define VMMETER_ALIGNED
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#endif
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/*
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* System wide statistics counters.
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* Locking:
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* c - constant after initialization
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* p - uses counter(9)
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*/
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struct vmmeter {
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/*
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* General system activity.
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*/
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counter_u64_t v_swtch; /* (p) context switches */
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counter_u64_t v_trap; /* (p) calls to trap */
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counter_u64_t v_syscall; /* (p) calls to syscall() */
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counter_u64_t v_intr; /* (p) device interrupts */
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counter_u64_t v_soft; /* (p) software interrupts */
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/*
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* Virtual memory activity.
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*/
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counter_u64_t v_vm_faults; /* (p) address memory faults */
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counter_u64_t v_io_faults; /* (p) page faults requiring I/O */
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counter_u64_t v_cow_faults; /* (p) copy-on-writes faults */
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counter_u64_t v_cow_optim; /* (p) optimized COW faults */
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counter_u64_t v_zfod; /* (p) pages zero filled on demand */
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counter_u64_t v_ozfod; /* (p) optimized zero fill pages */
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counter_u64_t v_swapin; /* (p) swap pager pageins */
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counter_u64_t v_swapout; /* (p) swap pager pageouts */
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counter_u64_t v_swappgsin; /* (p) swap pager pages paged in */
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counter_u64_t v_swappgsout; /* (p) swap pager pages paged out */
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counter_u64_t v_vnodein; /* (p) vnode pager pageins */
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counter_u64_t v_vnodeout; /* (p) vnode pager pageouts */
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counter_u64_t v_vnodepgsin; /* (p) vnode_pager pages paged in */
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counter_u64_t v_vnodepgsout; /* (p) vnode pager pages paged out */
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counter_u64_t v_intrans; /* (p) intransit blocking page faults */
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counter_u64_t v_reactivated; /* (p) reactivated by the pagedaemon */
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counter_u64_t v_pdwakeups; /* (p) times daemon has awaken */
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counter_u64_t v_pdpages; /* (p) pages analyzed by daemon */
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counter_u64_t v_pdshortfalls; /* (p) page reclamation shortfalls */
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counter_u64_t v_dfree; /* (p) pages freed by daemon */
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counter_u64_t v_pfree; /* (p) pages freed by processes */
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counter_u64_t v_tfree; /* (p) total pages freed */
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/*
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* Fork/vfork/rfork activity.
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*/
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counter_u64_t v_forks; /* (p) fork() calls */
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counter_u64_t v_vforks; /* (p) vfork() calls */
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counter_u64_t v_rforks; /* (p) rfork() calls */
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counter_u64_t v_kthreads; /* (p) fork() calls by kernel */
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counter_u64_t v_forkpages; /* (p) pages affected by fork() */
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counter_u64_t v_vforkpages; /* (p) pages affected by vfork() */
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counter_u64_t v_rforkpages; /* (p) pages affected by rfork() */
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counter_u64_t v_kthreadpages; /* (p) ... and by kernel fork() */
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counter_u64_t v_wire_count; /* (p) pages wired down */
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#define VM_METER_NCOUNTERS \
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(offsetof(struct vmmeter, v_page_size) / sizeof(counter_u64_t))
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/*
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* Distribution of page usages.
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*/
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u_int v_page_size; /* (c) page size in bytes */
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u_int v_page_count; /* (c) total number of pages in system */
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u_int v_free_reserved; /* (c) pages reserved for deadlock */
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u_int v_free_target; /* (c) pages desired free */
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u_int v_free_min; /* (c) pages desired free */
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u_int v_inactive_target; /* (c) pages desired inactive */
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u_int v_pageout_free_min; /* (c) min pages reserved for kernel */
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u_int v_interrupt_free_min; /* (c) reserved pages for int code */
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u_int v_free_severe; /* (c) severe page depletion point */
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};
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#endif /* _KERNEL || _WANT_VMMETER */
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#ifdef _KERNEL
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#include <sys/domainset.h>
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extern struct vmmeter vm_cnt;
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extern domainset_t all_domains;
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extern domainset_t vm_min_domains;
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extern domainset_t vm_severe_domains;
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#define VM_CNT_ADD(var, x) counter_u64_add(vm_cnt.var, x)
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#define VM_CNT_INC(var) VM_CNT_ADD(var, 1)
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#define VM_CNT_FETCH(var) counter_u64_fetch(vm_cnt.var)
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extern u_long vm_user_wire_count;
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static inline void
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vm_wire_add(int cnt)
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{
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VM_CNT_ADD(v_wire_count, cnt);
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}
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static inline void
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vm_wire_sub(int cnt)
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{
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VM_CNT_ADD(v_wire_count, -cnt);
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}
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u_int vm_free_count(void);
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static inline u_int
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vm_wire_count(void)
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{
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return (VM_CNT_FETCH(v_wire_count));
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}
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/*
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* Return TRUE if we are under our severe low-free-pages threshold
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*
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* These routines are typically used at the user<->system interface to determine
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* whether we need to block in order to avoid a low memory deadlock.
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*/
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static inline int
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vm_page_count_severe(void)
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{
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return (!DOMAINSET_EMPTY(&vm_severe_domains));
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}
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static inline int
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vm_page_count_severe_domain(int domain)
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{
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return (DOMAINSET_ISSET(domain, &vm_severe_domains));
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}
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static inline int
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vm_page_count_severe_set(const domainset_t *mask)
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{
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return (DOMAINSET_SUBSET(&vm_severe_domains, mask));
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}
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/*
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* Return TRUE if we are under our minimum low-free-pages threshold.
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*
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* These routines are typically used within the system to determine whether
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* we can execute potentially very expensive code in terms of memory. It
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* is also used by the pageout daemon to calculate when to sleep, when
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* to wake waiters up, and when (after making a pass) to become more
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* desperate.
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*/
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static inline int
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vm_page_count_min(void)
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{
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return (!DOMAINSET_EMPTY(&vm_min_domains));
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}
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static inline int
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vm_page_count_min_domain(int domain)
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{
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return (DOMAINSET_ISSET(domain, &vm_min_domains));
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}
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static inline int
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vm_page_count_min_set(const domainset_t *mask)
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{
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return (DOMAINSET_SUBSET(&vm_min_domains, mask));
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}
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#endif /* _KERNEL */
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#endif /* _SYS_VMMETER_H_ */
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