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ways: (1) Cached pages are no longer kept in the object's resident page splay tree and memq. Instead, they are kept in a separate per-object splay tree of cached pages. However, access to this new per-object splay tree is synchronized by the _free_ page queues lock, not to be confused with the heavily contended page queues lock. Consequently, a cached page can be reclaimed by vm_page_alloc(9) without acquiring the object's lock or the page queues lock. This solves a problem independently reported by tegge@ and Isilon. Specifically, they observed the page daemon consuming a great deal of CPU time because of pages bouncing back and forth between the cache queue (PQ_CACHE) and the inactive queue (PQ_INACTIVE). The source of this problem turned out to be a deadlock avoidance strategy employed when selecting a cached page to reclaim in vm_page_select_cache(). However, the root cause was really that reclaiming a cached page required the acquisition of an object lock while the page queues lock was already held. Thus, this change addresses the problem at its root, by eliminating the need to acquire the object's lock. Moreover, keeping cached pages in the object's primary splay tree and memq was, in effect, optimizing for the uncommon case. Cached pages are reclaimed far, far more often than they are reactivated. Instead, this change makes reclamation cheaper, especially in terms of synchronization overhead, and reactivation more expensive, because reactivated pages will have to be reentered into the object's primary splay tree and memq. (2) Cached pages are now stored alongside free pages in the physical memory allocator's buddy queues, increasing the likelihood that large allocations of contiguous physical memory (i.e., superpages) will succeed. Finally, as a result of this change long-standing restrictions on when and where a cached page can be reclaimed and returned by vm_page_alloc(9) are eliminated. Specifically, calls to vm_page_alloc(9) specifying VM_ALLOC_INTERRUPT can now reclaim and return a formerly cached page. Consequently, a call to malloc(9) specifying M_NOWAIT is less likely to fail. Discussed with: many over the course of the summer, including jeff@, Justin Husted @ Isilon, peter@, tegge@ Tested by: an earlier version by kris@ Approved by: re (kensmith)
136 lines
3.9 KiB
C
136 lines
3.9 KiB
C
/* $NetBSD: vmparam.h,v 1.26 2003/08/07 16:27:47 agc Exp $ */
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/*-
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* Copyright (c) 1988 The Regents of the University of California.
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* 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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* $FreeBSD$
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*/
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#ifndef _MACHINE_VMPARAM_H_
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#define _MACHINE_VMPARAM_H_
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/*#include <arm/arm32/vmparam.h>
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*/
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/*
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* Address space constants
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*/
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/*
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* The line between user space and kernel space
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* Mappings >= KERNEL_BASE are constant across all processes
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*/
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#define KERNBASE 0xc0000000
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/*
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* max number of non-contig chunks of physical RAM you can have
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*/
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#define VM_PHYSSEG_MAX 32
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/*
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* The physical address space is densely populated.
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*/
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#define VM_PHYSSEG_DENSE
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/*
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* Create three free page pools: VM_FREEPOOL_DEFAULT is the default pool
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* from which physical pages are allocated and VM_FREEPOOL_DIRECT is
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* the pool from which physical pages for small UMA objects are
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* allocated.
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*/
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#define VM_NFREEPOOL 3
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#define VM_FREEPOOL_CACHE 2
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#define VM_FREEPOOL_DEFAULT 0
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#define VM_FREEPOOL_DIRECT 1
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/*
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* we support 2 free lists:
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*
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* - DEFAULT for all systems
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* - ISADMA for the ISA DMA range on Sharks only
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*/
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#define VM_NFREELIST 2
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#define VM_FREELIST_DEFAULT 0
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#define VM_FREELIST_ISADMA 1
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/*
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* The largest allocation size is 1MB.
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*/
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#define VM_NFREEORDER 9
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#define UPT_MAX_ADDRESS VADDR(UPTPTDI + 3, 0)
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#define UPT_MIN_ADDRESS VADDR(UPTPTDI, 0)
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#define VM_MIN_ADDRESS (0x00001000)
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#ifdef ARM_USE_SMALL_ALLOC
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#ifndef ARM_KERN_DIRECTMAP
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#define ARM_KERN_DIRECTMAP 512 * 1024 * 1024 /* 512 MB */
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#endif
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#define VM_MAXUSER_ADDRESS KERNBASE - ARM_KERN_DIRECTMAP
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#else /* ARM_USE_SMALL_ALLOC */
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#define VM_MAXUSER_ADDRESS KERNBASE
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#endif /* ARM_USE_SMALL_ALLOC */
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#define VM_MAX_ADDRESS VM_MAXUSER_ADDRESS
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#define USRSTACK VM_MAXUSER_ADDRESS
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/* initial pagein size of beginning of executable file */
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#ifndef VM_INITIAL_PAGEIN
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#define VM_INITIAL_PAGEIN 16
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#endif
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#ifndef VM_MIN_KERNEL_ADDRESS
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#define VM_MIN_KERNEL_ADDRESS KERNBASE
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#endif
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#define VM_MAX_KERNEL_ADDRESS 0xffffffff
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/*
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* Virtual size (bytes) for various kernel submaps.
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*/
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#ifndef VM_KMEM_SIZE
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#define VM_KMEM_SIZE (12*1024*1024)
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#endif
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#define MAXTSIZ (16*1024*1024)
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#define DFLDSIZ (128*1024*1024)
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#define MAXDSIZ (512*1024*1024)
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#define DFLSSIZ (2*1024*1024)
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#define MAXSSIZ (8*1024*1024)
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#define SGROWSIZ (128*1024)
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#define MAXSLP 20
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#define VM_PROT_READ_IS_EXEC
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#ifdef ARM_USE_SMALL_ALLOC
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#define UMA_MD_SMALL_ALLOC
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#endif /* ARM_USE_SMALL_ALLOC */
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#endif /* _MACHINE_VMPARAM_H_ */
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