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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)
141 lines
4.4 KiB
C
141 lines
4.4 KiB
C
/* $FreeBSD$ */
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/* From: NetBSD: param.h,v 1.20 1997/09/19 13:52:53 leo Exp */
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/*
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* Copyright (c) 1988 University of Utah.
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. 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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* the Systems Programming Group of the University of Utah Computer
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* Science Department and Ralph Campbell.
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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: Utah $Hdr: machparam.h 1.11 89/08/14$
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*
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* @(#)param.h 8.1 (Berkeley) 6/10/93
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*/
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/*
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* Machine dependent constants for the Alpha.
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*/
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/*
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* Round p (pointer or byte index) up to a correctly-aligned value for all
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* data types (int, long, ...). The result is u_long and must be cast to
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* any desired pointer type.
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*
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* ALIGNED_POINTER is a boolean macro that checks whether an address
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* is valid to fetch data elements of type t from on this architecture.
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* This does not reflect the optimal alignment, just the possibility
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* (within reasonable limits).
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*
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*/
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#ifndef _ALIGNBYTES
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#define _ALIGNBYTES 7
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#endif
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#ifndef _ALIGN
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#define _ALIGN(p) (((u_long)(p) + _ALIGNBYTES) &~ _ALIGNBYTES)
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#endif
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#ifndef _ALIGNED_POINTER
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#define _ALIGNED_POINTER(p,t) ((((u_long)(p)) & (sizeof(t)-1)) == 0)
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#endif
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#ifndef _MACHINE
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#define _MACHINE alpha
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#endif
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#ifndef _MACHINE_ARCH
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#define _MACHINE_ARCH alpha
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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 "alpha"
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#endif
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#ifndef MACHINE_ARCH
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#define MACHINE_ARCH "alpha"
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#endif
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#define MID_MACHINE MID_ALPHA
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#include <machine/alpha_cpu.h>
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#include <machine/cpu.h>
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#define MAXSMPCPU 8
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#ifdef SMP
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#define MAXCPU MAXSMPCPU
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#else
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#define MAXCPU 1
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#endif
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#define ALIGNBYTES _ALIGNBYTES
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#define ALIGN(p) _ALIGN(p)
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#define ALIGNED_POINTER(p,t) _ALIGNED_POINTER(p,t)
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#define PAGE_SIZE (1 << ALPHA_PGSHIFT) /* bytes/page */
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#define PAGE_SHIFT ALPHA_PGSHIFT
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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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#define KERNBASE 0xfffffc0000300000LL /* start of kernel virtual */
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#define BTOPKERNBASE ((u_long)KERNBASE >> PGSHIFT)
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#define CLSIZE 1
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#define CLSIZELOG2 0
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/* NOTE: SSIZE, SINCR and UPAGES must be multiples of CLSIZE */
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#define SSIZE 1 /* initial stack size/NBPG */
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#define SINCR 1 /* increment of stack/NBPG */
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#define PREEMPTION
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#ifndef KSTACK_PAGES
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#define KSTACK_PAGES 2 /* pages of kstack (with 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 /* pages of u-area */
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/*
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* Mach derived conversion macros
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*/
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#define round_page(x) ((((unsigned long)(x)) + PAGE_MASK) & ~(PAGE_MASK))
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#define trunc_page(x) ((unsigned long)(x) & ~(PAGE_MASK))
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#define atop(x) ((unsigned long)(x) >> PAGE_SHIFT)
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#define ptoa(x) ((unsigned long)(x) << PAGE_SHIFT)
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#define alpha_btop(x) ((unsigned long)(x) >> PAGE_SHIFT)
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#define alpha_ptob(x) ((unsigned long)(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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