/* $NetBSD: uvm_pglist.h,v 1.11 2020/04/13 15:16:14 ad Exp $ */
/*-
* Copyright (c) 2000, 2001, 2008, 2019 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe, and by Andrew Doran.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* This defines the type of a page queue, e.g. active list, inactive
* list, etc.
*/
struct vm_page;
TAILQ_HEAD(pglist, vm_page);
LIST_HEAD(pgflist, vm_page);
/*
* The global uvm.page_free list (uvm_page.c, uvm_pglist.c). Free pages are
* stored according to freelist, bucket, and cache colour.
*
* pglist = &uvm.page_free[freelist].pgfl_buckets[bucket].pgb_color[color];
*
* Freelists provide a priority ordering of pages for allocation, based upon
* how valuable they are for special uses (e.g. device driver DMA). MD
* code decides the number and structure of these. They are always arranged
* in descending order of allocation priority.
*
* Pages are then grouped in buckets according to some common factor, for
* example L2/L3 cache locality. Each bucket has its own lock, and the
* locks are shared among freelists for the same numbered buckets.
*
* Inside each bucket, pages are further distributed by cache color.
*
* We want these data structures to occupy as few cache lines as possible,
* as they will be highly contended.
*/
struct pgflbucket {
uintptr_t pgb_nfree; /* total # free pages, all colors */
struct pgflist pgb_colors[1]; /* variable size array */
};
/*
* 8 buckets should be enough to cover most all current x86 systems (2019),
* given the way package/core/smt IDs are structured on x86. For systems
* that report high package counts despite having a single physical CPU
* package (e.g. Ampere eMAG) a little bit of sharing isn't going to hurt.
*/
#define PGFL_MAX_BUCKETS 8
struct pgfreelist {
struct pgflbucket *pgfl_buckets[PGFL_MAX_BUCKETS];
};
/*
* Lock for each bucket.
*/
union uvm_freelist_lock {
kmutex_t lock;
uint8_t padding[COHERENCY_UNIT];
};
extern union uvm_freelist_lock uvm_freelist_locks[PGFL_MAX_BUCKETS];
