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	The cv_timedwait() function by definition must wait unconditionally for cv_signal()/cv_broadcast() before waking. This causes processes to go in the D state which increases the load average. The load average is the summation of processes in D state and run queue. To avoid this it can be desirable to sleep interruptibly. These processes do not count against the load average but may be woken by a signal. It is up to the caller to determine why the process was woken it may be for one of three reasons. 1) cv_signal()/cv_broadcast() 2) the timeout expired 3) a signal was received Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
		
			
				
	
	
		
			78 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
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			78 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*****************************************************************************\
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 *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
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 *  Copyright (C) 2007 The Regents of the University of California.
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 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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 *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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 *  UCRL-CODE-235197
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 *
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 *  This file is part of the SPL, Solaris Porting Layer.
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 *  For details, see <http://github.com/behlendorf/spl/>.
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 *
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 *  The SPL is free software; you can redistribute it and/or modify it
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 *  under the terms of the GNU General Public License as published by the
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 *  Free Software Foundation; either version 2 of the License, or (at your
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 *  option) any later version.
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 *
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 *  The SPL is distributed in the hope that it will be useful, but WITHOUT
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 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 *  for more details.
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 *
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 *  You should have received a copy of the GNU General Public License along
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 *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
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\*****************************************************************************/
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#ifndef _SPL_CONDVAR_H
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#define _SPL_CONDVAR_H
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#include <linux/module.h>
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#include <linux/wait.h>
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#include <sys/kmem.h>
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#include <sys/mutex.h>
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/*
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 * The kcondvar_t struct is protected by mutex taken externally before
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 * calling any of the wait/signal funs, and passed into the wait funs.
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 */
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#define CV_MAGIC			0x346545f4
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#define CV_POISON			0x95
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typedef struct {
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	int cv_magic;
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	char *cv_name;
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	int cv_name_size;
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	wait_queue_head_t cv_event;
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	atomic_t cv_waiters;
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	kmutex_t *cv_mutex;
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} kcondvar_t;
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typedef enum { CV_DEFAULT=0, CV_DRIVER } kcv_type_t;
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extern void __cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg);
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extern void __cv_destroy(kcondvar_t *cvp);
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extern void __cv_wait(kcondvar_t *cvp, kmutex_t *mp);
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extern void __cv_wait_interruptible(kcondvar_t *cvp, kmutex_t *mp);
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extern clock_t __cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time);
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extern clock_t __cv_timedwait_interruptible(kcondvar_t *cvp, kmutex_t *mp,
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	clock_t exp_time);
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extern void __cv_signal(kcondvar_t *cvp);
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extern void __cv_broadcast(kcondvar_t *cvp);
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#define cv_init(cvp, name, type, arg)                                         \
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({                                                                            \
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	if ((name) == NULL)                                                   \
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		__cv_init(cvp, #cvp, type, arg);                              \
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	else                                                                  \
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		__cv_init(cvp, name, type, arg);                              \
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})
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#define cv_destroy(cvp)				__cv_destroy(cvp)
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#define cv_wait(cvp, mp)			__cv_wait(cvp, mp)
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#define cv_wait_interruptible(cvp, mp)		__cv_wait_interruptible(cvp,mp)
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#define cv_timedwait(cvp, mp, t)		__cv_timedwait(cvp, mp, t)
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#define cv_timedwait_interruptible(cvp, mp, t)                                \
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	__cv_timedwait_interruptible(cvp, mp, t)
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#define cv_signal(cvp)				__cv_signal(cvp)
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#define cv_broadcast(cvp)			__cv_broadcast(cvp)
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#endif /* _SPL_CONDVAR_H */
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