Source to kern/mach_factor.c


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/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @[email protected]
 * 
 * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
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 * Source License Version 1.0 (the 'License').  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
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 * this file.
 * 
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 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
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 * 
 * @[email protected]
 */

/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  [email protected]
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 *	File:	kern/mach_factor.c
 *	Author:	Avadis Tevanian, Jr.
 *	Date:	1986
 *
 *	Compute the Mach Factor.
 */

#include <cpus.h>

#include <mach/machine.h>
#include <mach/processor_info.h>
#include <kern/sched.h>
#include <kern/processor.h>
#include <kern/time_out.h>

long	avenrun[3] = {0, 0, 0};
long	mach_factor[3] = {0, 0, 0};

/*
 * Values are scaled by LOAD_SCALE, defined in processor_info.h
 */
static	long	fract[3] = {
	800,			/* (4.0/5.0) 5 second average */
	966,			/* (29.0/30.0) 30 second average */
	983,			/* (59.0/60.) 1 minute average */
};

void compute_mach_factor()
{
	register processor_set_t	pset;
	register processor_t		processor;
	register int		ncpus;
	register int		nthreads;
	register long		factor_now;
	register long		average_now;
	register long		load_now;

	simple_lock(&all_psets_lock);
	pset = (processor_set_t) queue_first(&all_psets);
	while (!queue_end(&all_psets, (queue_entry_t)pset)) {

	    /*
	     *	If no processors, this pset is in suspended animation.
	     *	No load calculations are performed.
	     */
	    pset_lock(pset);
	    if((ncpus = pset->processor_count) > 0) {

		/*
		 *	Count number of threads.
		 */
		nthreads = pset->runq.count;
		processor = (processor_t) queue_first(&pset->processors);
		while (!queue_end(&pset->processors,
		    (queue_entry_t)processor)) {
			nthreads += processor->runq.count;
			processor =
			    (processor_t) queue_next(&processor->processors);
		}

		/*
		 * account for threads on cpus.
		 */
		nthreads += ncpus - pset->idle_count; 

		/*
		 *	The current thread (running this calculation)
		 *	doesn't count; it's always in the default pset.
		 */
		if (pset == &default_pset)
		   nthreads -= 1;

		if (nthreads > ncpus) {
			factor_now = (ncpus * LOAD_SCALE) / (nthreads + 1);
			load_now = (nthreads << SCHED_SHIFT) / ncpus;
		}
		else {
			factor_now = (ncpus - nthreads) * LOAD_SCALE;
			load_now = SCHED_SCALE;
		}

		/*
		 *	Load average and mach factor calculations for
		 *	those that ask about these things.
		 */

		average_now = nthreads * LOAD_SCALE;

		pset->mach_factor =
			((pset->mach_factor << 2) + factor_now)/5;
		pset->load_average =
			((pset->load_average << 2) + average_now)/5;

		/*
		 *	And some ugly stuff to keep w happy.
		 */
		if (pset == &default_pset) {
		    register int i;

		    for (i = 0; i < 3; i++) {
			mach_factor[i] = ( (mach_factor[i]*fract[i])
				 + (factor_now*(LOAD_SCALE-fract[i])) )
				/ LOAD_SCALE;
			avenrun[i] = ( (avenrun[i]*fract[i])
				 + (average_now*(LOAD_SCALE-fract[i])) )
				/ LOAD_SCALE;
		    }
		}

		/*
		 *	sched_load is the only thing used by scheduler.
		 *	It is always at least 1 (i.e. SCHED_SCALE).
		 */
		pset->sched_load = (pset->sched_load + load_now) >> 1;
	    }

	    pset_unlock(pset);
	    pset = (processor_set_t) queue_next(&pset->all_psets);
	}

	simple_unlock(&all_psets_lock);
}