/*-
* SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
*
* 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.
* 3. 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_page.h 8.2 (Berkeley) 12/13/93
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* 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_PAGEQUEUE_
#define _VM_PAGEQUEUE_
#ifdef _KERNEL
struct vm_pagequeue {
struct mtx pq_mutex;
struct pglist pq_pl;
int pq_cnt;
const char * const pq_name;
uint64_t pq_pdpages;
} __aligned(CACHE_LINE_SIZE);
#ifndef VM_BATCHQUEUE_SIZE
#define VM_BATCHQUEUE_SIZE 7
#endif
struct vm_batchqueue {
vm_page_t bq_pa[VM_BATCHQUEUE_SIZE];
int bq_cnt;
} __aligned(CACHE_LINE_SIZE);
#include <vm/uma.h>
#include <sys/_blockcount.h>
#include <sys/pidctrl.h>
struct sysctl_oid;
/*
* One vm_domain per NUMA domain. Contains pagequeues, free page structures,
* and accounting.
*
* Lock Key:
* f vmd_free_mtx
* p vmd_pageout_mtx
* d vm_domainset_lock
* a atomic
* c const after boot
* q page queue lock
*
* A unique page daemon thread manages each vm_domain structure and is
* responsible for ensuring that some free memory is available by freeing
* inactive pages and aging active pages. To decide how many pages to process,
* it uses thresholds derived from the number of pages in the domain:
*
* vmd_page_count
* ---
* |
* |-> vmd_inactive_target (~3%)
* | - The active queue scan target is given by
* | (vmd_inactive_target + vmd_free_target - vmd_free_count).
* |
* |
* |-> vmd_free_target (~2%)
* | - Target for page reclamation.
* |
* |-> vmd_pageout_wakeup_thresh (~1.8%)
* | - Threshold for waking up the page daemon.
* |
* |
* |-> vmd_free_min (~0.5%)
* | - First low memory threshold.
* | - Causes per-CPU caching to be lazily disabled in UMA.
* | - vm_wait() sleeps below this threshold.
* |
* |-> vmd_free_severe (~0.25%)
* | - Second low memory threshold.
* | - Triggers aggressive UMA reclamation, disables delayed buffer
* | writes.
* |
* |-> vmd_free_reserved (~0.13%)
* | - Minimum for VM_ALLOC_NORMAL page allocations.
* |-> vmd_pageout_free_min (32 + 2 pages)
* | - Minimum for waking a page daemon thread sleeping in vm_wait().
* |-> vmd_interrupt_free_min (2 pages)
* | - Minimum for VM_ALLOC_SYSTEM page allocations.
* ---
*
*--
* Free page count regulation:
*
* The page daemon attempts to ensure that the free page count is above the free
* target. It wakes up periodically (every 100ms) to input the current free
* page shortage (free_target - free_count) to a PID controller, which in
* response outputs the number of pages to attempt to reclaim. The shortage's
* current magnitude, rate of change, and cumulative value are together used to
* determine the controller's output. The page daemon target thus adapts
* dynamically to the system's demand for free pages, resulting in less
* burstiness than a simple hysteresis loop.
*
* When the free page count drops below the wakeup threshold,
* vm_domain_allocate() proactively wakes up the page daemon. This helps ensure
* that the system responds promptly to a large instantaneous free page
* shortage.
*
* The page daemon also attempts to ensure that some fraction of the system's
* memory is present in the inactive (I) and laundry (L) page queues, so that it
* can respond promptly to a sudden free page shortage. In particular, the page
* daemon thread aggressively scans active pages so long as the following
* condition holds:
*
* len(I) + len(L) + free_target - free_count < inactive_target
*
* Otherwise, when the inactive target is met, the page daemon periodically
* scans a small portion of the active queue in order to maintain up-to-date
* per-page access history. Unreferenced pages in the active queue thus
* eventually migrate to the inactive queue.
*
* The per-domain laundry thread periodically launders dirty pages based on the
* number of clean pages freed by the page daemon since the last laundering. If
* the page daemon fails to meet its scan target (i.e., the PID controller
* output) because of a shortage of clean inactive pages, the laundry thread
* attempts to launder enough pages to meet the free page target.
*
*--
* Page allocation priorities:
*
* The system defines three page allocation priorities: VM_ALLOC_NORMAL,
* VM_ALLOC_SYSTEM and VM_ALLOC_INTERRUPT. An interrupt-priority allocation can
* claim any free page. This priority is used in the pmap layer when attempting
* to allocate a page for the kernel page tables; in such cases an allocation
* failure will usually result in a kernel panic. The system priority is used
* for most other kernel memory allocations, for instance by UMA's slab
* allocator or the buffer cache. Such allocations will fail if the free count
* is below interrupt_free_min. All other allocations occur at the normal
* priority, which is typically used for allocation of user pages, for instance
* in the page fault handler or when allocating page table pages or pv_entry
* structures for user pmaps. Such allocations fail if the free count is below
* the free_reserved threshold.
*
*--
* Free memory shortages:
*
* The system uses the free_min and free_severe thresholds to apply
* back-pressure and give the page daemon a chance to recover. When a page
* allocation fails due to a shortage and the allocating thread cannot handle
* failure, it may call vm_wait() to sleep until free pages are available.
* vm_domain_freecnt_inc() wakes sleeping threads once the free page count rises
* above the free_min threshold; the page daemon and laundry threads are given
* priority and will wake up once free_count reaches the (much smaller)
* pageout_free_min threshold.
*
* On NUMA systems, the domainset iterators always prefer NUMA domains where the
* free page count is above the free_min threshold. This means that given the
* choice between two NUMA domains, one above the free_min threshold and one
* below, the former will be used to satisfy the allocation request regardless
* of the domain selection policy.
*
* In addition to reclaiming memory from the page queues, the vm_lowmem event
* fires every ten seconds so long as the system is under memory pressure (i.e.,
* vmd_free_count < vmd_free_target). This allows kernel subsystems to register
* for notifications of free page shortages, upon which they may shrink their
* caches. Following a vm_lowmem event, UMA's caches are pruned to ensure that
* they do not contain an excess of unused memory. When a domain is below the
* free_min threshold, UMA limits the population of per-CPU caches. When a
* domain falls below the free_severe threshold, UMA's caches are completely
* drained.
*
* If the system encounters a global memory shortage, it may resort to the
* out-of-memory (OOM) killer, which selects a process and delivers SIGKILL in a
* last-ditch attempt to free up some pages. Either of the two following
* conditions will activate the OOM killer:
*
* 1. The page daemons collectively fail to reclaim any pages during their
* inactive queue scans. After vm_pageout_oom_seq consecutive scans fail,
* the page daemon thread votes for an OOM kill, and an OOM kill is
* triggered when all page daemons have voted. This heuristic is strict and
* may fail to trigger even when the system is effectively deadlocked.
*
* 2. Threads in the user fault handler are repeatedly unable to make progress
* while allocating a page to satisfy the fault. After
* vm_pfault_oom_attempts page allocation failures with intervening
* vm_wait() calls, the faulting thread will trigger an OOM kill.
*/
struct vm_domain {
struct vm_pagequeue vmd_pagequeues[PQ_COUNT];
struct mtx_padalign vmd_free_mtx;
struct mtx_padalign vmd_pageout_mtx;
struct vm_pgcache {
int domain;
int pool;
uma_zone_t zone;
} vmd_pgcache[VM_NFREEPOOL];
struct vmem *vmd_kernel_arena; /* (c) per-domain kva R/W arena. */
struct vmem *vmd_kernel_rwx_arena; /* (c) per-domain kva R/W/X arena. */
u_int vmd_domain; /* (c) Domain number. */
u_int vmd_page_count; /* (c) Total page count. */
long vmd_segs; /* (c) bitmask of the segments */
u_int __aligned(CACHE_LINE_SIZE) vmd_free_count; /* (a,f) free page count */
u_int vmd_pageout_deficit; /* (a) Estimated number of pages deficit */
uint8_t vmd_pad[CACHE_LINE_SIZE - (sizeof(u_int) * 2)];
/* Paging control variables, used within single threaded page daemon. */
struct pidctrl vmd_pid; /* Pageout controller. */
boolean_t vmd_oom;
u_int vmd_inactive_threads;
u_int vmd_inactive_shortage; /* Per-thread shortage. */
blockcount_t vmd_inactive_running; /* Number of inactive threads. */
blockcount_t vmd_inactive_starting; /* Number of threads started. */
volatile u_int vmd_addl_shortage; /* Shortage accumulator. */
volatile u_int vmd_inactive_freed; /* Successful inactive frees. */
volatile u_int vmd_inactive_us; /* Microseconds for above. */
u_int vmd_inactive_pps; /* Exponential decay frees/second. */
int vmd_oom_seq;
int vmd_last_active_scan;
struct vm_page vmd_markers[PQ_COUNT]; /* (q) markers for queue scans */
struct vm_page vmd_inacthead; /* marker for LRU-defeating insertions */
struct vm_page vmd_clock[2]; /* markers for active queue scan */
int vmd_pageout_wanted; /* (a, p) pageout daemon wait channel */
int vmd_pageout_pages_needed; /* (d) page daemon waiting for pages? */
bool vmd_minset; /* (d) Are we in vm_min_domains? */
bool vmd_severeset; /* (d) Are we in vm_severe_domains? */
enum {
VM_LAUNDRY_IDLE = 0,
VM_LAUNDRY_BACKGROUND,
VM_LAUNDRY_SHORTFALL
} vmd_laundry_request;
/* Paging thresholds and targets. */
u_int vmd_clean_pages_freed; /* (q) accumulator for laundry thread */
u_int vmd_background_launder_target; /* (c) */
u_int vmd_free_reserved; /* (c) pages reserved for deadlock */
u_int vmd_free_target; /* (c) pages desired free */
u_int vmd_free_min; /* (c) pages desired free */
u_int vmd_inactive_target; /* (c) pages desired inactive */
u_int vmd_pageout_free_min; /* (c) min pages reserved for kernel */
u_int vmd_pageout_wakeup_thresh;/* (c) min pages to wake pagedaemon */
u_int vmd_interrupt_free_min; /* (c) reserved pages for int code */
u_int vmd_free_severe; /* (c) severe page depletion point */
/* Name for sysctl etc. */
struct sysctl_oid *vmd_oid;
char vmd_name[sizeof(__XSTRING(MAXMEMDOM))];
} __aligned(CACHE_LINE_SIZE);
extern struct vm_domain vm_dom[MAXMEMDOM];
#define VM_DOMAIN(n) (&vm_dom[(n)])
#define VM_DOMAIN_EMPTY(n) (vm_dom[(n)].vmd_page_count == 0)
#define vm_pagequeue_assert_locked(pq) mtx_assert(&(pq)->pq_mutex, MA_OWNED)
#define vm_pagequeue_lock(pq) mtx_lock(&(pq)->pq_mutex)
#define vm_pagequeue_lockptr(pq) (&(pq)->pq_mutex)
#define vm_pagequeue_trylock(pq) mtx_trylock(&(pq)->pq_mutex)
#define vm_pagequeue_unlock(pq) mtx_unlock(&(pq)->pq_mutex)
#define vm_domain_free_assert_locked(n) \
mtx_assert(vm_domain_free_lockptr((n)), MA_OWNED)
#define vm_domain_free_assert_unlocked(n) \
mtx_assert(vm_domain_free_lockptr((n)), MA_NOTOWNED)
#define vm_domain_free_lock(d) \
mtx_lock(vm_domain_free_lockptr((d)))
#define vm_domain_free_lockptr(d) \
(&(d)->vmd_free_mtx)
#define vm_domain_free_trylock(d) \
mtx_trylock(vm_domain_free_lockptr((d)))
#define vm_domain_free_unlock(d) \
mtx_unlock(vm_domain_free_lockptr((d)))
#define vm_domain_pageout_lockptr(d) \
(&(d)->vmd_pageout_mtx)
#define vm_domain_pageout_assert_locked(n) \
mtx_assert(vm_domain_pageout_lockptr((n)), MA_OWNED)
#define vm_domain_pageout_assert_unlocked(n) \
mtx_assert(vm_domain_pageout_lockptr((n)), MA_NOTOWNED)
#define vm_domain_pageout_lock(d) \
mtx_lock(vm_domain_pageout_lockptr((d)))
#define vm_domain_pageout_unlock(d) \
mtx_unlock(vm_domain_pageout_lockptr((d)))
static __inline void
vm_pagequeue_cnt_add(struct vm_pagequeue *pq, int addend)
{
vm_pagequeue_assert_locked(pq);
pq->pq_cnt += addend;
}
#define vm_pagequeue_cnt_inc(pq) vm_pagequeue_cnt_add((pq), 1)
#define vm_pagequeue_cnt_dec(pq) vm_pagequeue_cnt_add((pq), -1)
static inline void
vm_pagequeue_remove(struct vm_pagequeue *pq, vm_page_t m)
{
TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
vm_pagequeue_cnt_dec(pq);
}
static inline void
vm_batchqueue_init(struct vm_batchqueue *bq)
{
bq->bq_cnt = 0;
}
static inline bool
vm_batchqueue_insert(struct vm_batchqueue *bq, vm_page_t m)
{
if (bq->bq_cnt < nitems(bq->bq_pa)) {
bq->bq_pa[bq->bq_cnt++] = m;
return (true);
}
return (false);
}
static inline vm_page_t
vm_batchqueue_pop(struct vm_batchqueue *bq)
{
if (bq->bq_cnt == 0)
return (NULL);
return (bq->bq_pa[--bq->bq_cnt]);
}
void vm_domain_set(struct vm_domain *vmd);
void vm_domain_clear(struct vm_domain *vmd);
int vm_domain_allocate(struct vm_domain *vmd, int req, int npages);
/*
* vm_pagequeue_domain:
*
* Return the memory domain the page belongs to.
*/
static inline struct vm_domain *
vm_pagequeue_domain(vm_page_t m)
{
return (VM_DOMAIN(vm_page_domain(m)));
}
/*
* Return the number of pages we need to free-up or cache
* A positive number indicates that we do not have enough free pages.
*/
static inline int
vm_paging_target(struct vm_domain *vmd)
{
return (vmd->vmd_free_target - vmd->vmd_free_count);
}
/*
* Returns TRUE if the pagedaemon needs to be woken up.
*/
static inline int
vm_paging_needed(struct vm_domain *vmd, u_int free_count)
{
return (free_count < vmd->vmd_pageout_wakeup_thresh);
}
/*
* Returns TRUE if the domain is below the min paging target.
*/
static inline int
vm_paging_min(struct vm_domain *vmd)
{
return (vmd->vmd_free_min > vmd->vmd_free_count);
}
/*
* Returns TRUE if the domain is below the severe paging target.
*/
static inline int
vm_paging_severe(struct vm_domain *vmd)
{
return (vmd->vmd_free_severe > vmd->vmd_free_count);
}
/*
* Return the number of pages we need to launder.
* A positive number indicates that we have a shortfall of clean pages.
*/
static inline int
vm_laundry_target(struct vm_domain *vmd)
{
return (vm_paging_target(vmd));
}
void pagedaemon_wakeup(int domain);
static inline void
vm_domain_freecnt_inc(struct vm_domain *vmd, int adj)
{
u_int old, new;
old = atomic_fetchadd_int(&vmd->vmd_free_count, adj);
new = old + adj;
/*
* Only update bitsets on transitions. Notice we short-circuit the
* rest of the checks if we're above min already.
*/
if (old < vmd->vmd_free_min && (new >= vmd->vmd_free_min ||
(old < vmd->vmd_free_severe && new >= vmd->vmd_free_severe) ||
(old < vmd->vmd_pageout_free_min &&
new >= vmd->vmd_pageout_free_min)))
vm_domain_clear(vmd);
}
#endif /* _KERNEL */
#endif /* !_VM_PAGEQUEUE_ */
