0c0b25ae91
than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
145 lines
4.3 KiB
C
145 lines
4.3 KiB
C
/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* William Jolitz.
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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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* 4. 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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* from: @(#)param.h 5.8 (Berkeley) 6/28/91
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* $FreeBSD$
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*/
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/*
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* Machine dependent constants for Intel 386.
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*/
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/*
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* Round p (pointer or byte index) up to a correctly-aligned value
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* for all data types (int, long, ...). The result is unsigned int
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* and must be cast to any desired pointer type.
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*/
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#ifndef _ALIGNBYTES
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#define _ALIGNBYTES (sizeof(int) - 1)
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#endif
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#ifndef _ALIGN
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#define _ALIGN(p) (((unsigned)(p) + _ALIGNBYTES) & ~_ALIGNBYTES)
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#endif
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#ifndef _MACHINE
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#define _MACHINE i386
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#endif
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#ifndef _MACHINE_ARCH
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#define _MACHINE_ARCH i386
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#endif
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#ifndef _NO_NAMESPACE_POLLUTION
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#ifndef _MACHINE_PARAM_H_
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#define _MACHINE_PARAM_H_
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#ifndef MACHINE
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#define MACHINE "i386"
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#endif
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#ifndef MACHINE_ARCH
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#define MACHINE_ARCH "i386"
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#endif
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#define MID_MACHINE MID_I386
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#ifdef SMP
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#define MAXCPU 16
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#else
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#define MAXCPU 1
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#endif /* SMP */
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#define ALIGNBYTES _ALIGNBYTES
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#define ALIGN(p) _ALIGN(p)
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#define PAGE_SHIFT 12 /* LOG2(PAGE_SIZE) */
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#define PAGE_SIZE (1<<PAGE_SHIFT) /* bytes/page */
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#define PAGE_MASK (PAGE_SIZE-1)
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#define NPTEPG (PAGE_SIZE/(sizeof (pt_entry_t)))
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#ifdef PAE
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#define NPGPTD 4
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#define PDRSHIFT 21 /* LOG2(NBPDR) */
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#else
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#define NPGPTD 1
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#define PDRSHIFT 22 /* LOG2(NBPDR) */
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#endif
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#define NBPTD (NPGPTD<<PAGE_SHIFT)
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#define NPDEPTD (NBPTD/(sizeof (pd_entry_t)))
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#define NPDEPG (PAGE_SIZE/(sizeof (pd_entry_t)))
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#define NBPDR (1<<PDRSHIFT) /* bytes/page dir */
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#define PDRMASK (NBPDR-1)
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#define PREEMPTION
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#define IOPAGES 2 /* pages of i/o permission bitmap */
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#ifndef KSTACK_PAGES
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#define KSTACK_PAGES 2 /* Includes pcb! */
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#endif
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#define KSTACK_GUARD_PAGES 1 /* pages of kstack guard; 0 disables */
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#define UAREA_PAGES 1 /* holds struct user WITHOUT PCB (see def.) */
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/*
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* Ceiling on amount of swblock kva space, can be changed via
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* the kern.maxswzone /boot/loader.conf variable.
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*/
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#ifndef VM_SWZONE_SIZE_MAX
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#define VM_SWZONE_SIZE_MAX (32 * 1024 * 1024)
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#endif
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/*
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* Ceiling on size of buffer cache (really only effects write queueing,
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* the VM page cache is not effected), can be changed via
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* the kern.maxbcache /boot/loader.conf variable.
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*/
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#ifndef VM_BCACHE_SIZE_MAX
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#define VM_BCACHE_SIZE_MAX (200 * 1024 * 1024)
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#endif
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/*
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* Mach derived conversion macros
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*/
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#define trunc_page(x) ((x) & ~PAGE_MASK)
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#define round_page(x) (((x) + PAGE_MASK) & ~PAGE_MASK)
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#define trunc_4mpage(x) ((x) & ~PDRMASK)
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#define round_4mpage(x) ((((x)) + PDRMASK) & ~PDRMASK)
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#define atop(x) ((x) >> PAGE_SHIFT)
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#define ptoa(x) ((x) << PAGE_SHIFT)
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#define i386_btop(x) ((x) >> PAGE_SHIFT)
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#define i386_ptob(x) ((x) << PAGE_SHIFT)
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#define pgtok(x) ((x) * (PAGE_SIZE / 1024))
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#endif /* !_MACHINE_PARAM_H_ */
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#endif /* !_NO_NAMESPACE_POLLUTION */
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