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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)
147 lines
4.4 KiB
C
147 lines
4.4 KiB
C
/*-
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* Copyright (C) 1995, 1996 Wolfgang Solfrank.
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* Copyright (C) 1995, 1996 TooLs GmbH.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by TooLs GmbH.
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* 4. The name of TooLs GmbH may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $NetBSD: vmparam.h,v 1.11 2000/02/11 19:25:16 thorpej Exp $
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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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#define USRSTACK VM_MAXUSER_ADDRESS
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#ifndef MAXTSIZ
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#define MAXTSIZ (16*1024*1024) /* max text size */
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#endif
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#ifndef DFLDSIZ
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#define DFLDSIZ (32*1024*1024) /* default data size */
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#endif
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#ifndef MAXDSIZ
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#define MAXDSIZ (512*1024*1024) /* max data size */
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#endif
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#ifndef DFLSSIZ
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#define DFLSSIZ (1*1024*1024) /* default stack size */
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#endif
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#ifndef MAXSSIZ
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#define MAXSSIZ (32*1024*1024) /* max stack size */
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#endif
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/*
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* Size of shared memory map
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*/
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#ifndef SHMMAXPGS
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#define SHMMAXPGS 1024
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#endif
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/*
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* The time for a process to be blocked before being very swappable.
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* This is a number of seconds which the system takes as being a non-trivial
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* amount of real time. You probably shouldn't change this;
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* it is used in subtle ways (fractions and multiples of it are, that is, like
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* half of a ``long time'', almost a long time, etc.)
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* It is related to human patience and other factors which don't really
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* change over time.
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*/
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#define MAXSLP 20
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/*
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* Use the direct-mapped BAT registers for UMA small allocs. This
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* takes pressure off the small amount of available KVA.
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*/
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#define UMA_MD_SMALL_ALLOC
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/*
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* Would like to have MAX addresses = 0, but this doesn't (currently) work
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*/
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#define VM_MIN_ADDRESS ((vm_offset_t)0)
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#define VM_MAXUSER_ADDRESS ((vm_offset_t)0x7ffff000)
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#define VM_MAX_ADDRESS VM_MAXUSER_ADDRESS
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#define VM_MIN_KERNEL_ADDRESS ((vm_offset_t)(KERNEL_SR << ADDR_SR_SHFT))
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#define VM_MAX_KERNEL_ADDRESS (VM_MIN_KERNEL_ADDRESS + 2*SEGMENT_LENGTH - 1)
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#define KERNBASE 0x100000 /* start of kernel virtual */
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/* XXX max. amount of KVM to be used by buffers. */
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#ifndef VM_MAX_KERNEL_BUF
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#define VM_MAX_KERNEL_BUF (SEGMENT_LENGTH * 7 / 10)
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#endif
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struct pmap_physseg {
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struct pv_entry *pvent;
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char *attrs;
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};
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#define VM_PHYSSEG_MAX 16 /* 1? */
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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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* Create one free page list.
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*/
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#define VM_NFREELIST 1
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#define VM_FREELIST_DEFAULT 0
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/*
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* The largest allocation size is 4MB.
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*/
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#define VM_NFREEORDER 11
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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 SGROWSIZ
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#define SGROWSIZ (128UL*1024) /* amount to grow stack */
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#endif
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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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#endif /* _MACHINE_VMPARAM_H_ */
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