com.bigdata.bop.cost.DiskCostModel Maven / Gradle / Ivy

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/**

Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016.  All rights reserved.

Contact:
     SYSTAP, LLC DBA Blazegraph
     2501 Calvert ST NW #106
     Washington, DC 20008
     [email protected]

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
/*
 * Created on Sep 30, 2010
 */
package com.bigdata.bop.cost;

import java.io.Serializable;

/**
 * A cost model of the disk.
 * 
 * @todo Develop disk models for SAS,SATA,SSD and various RAID configurations,
 *       including the #of spindles in the RAID array.
 * @todo Develop disk models for SAN, NAS, NFS, parallel file systems, etc.
 * @todo Conditionally copy the desired disk model parameters into the fields
 *       above to see the performance estimates for a given configuration.
 * @todo The scattered and sustained write rates can be estimated from the
 *       transfer rate. However, SCSI does much better than SATA when it can
 *       reorder the writes for improved locality.
 */
public class DiskCostModel implements Serializable {

	/**
	 * @todo should be either Externalizable and explicitly managed versioning
	 *       or Serializable with a public interface for versioning.
	 */
	private static final long serialVersionUID = 1L;

	public static final DiskCostModel DEFAULT = new DiskCostModel(10d, 41943040);

    /**
     * The average disk seek time (milliseconds).
     */
    final public double seekTime;

    /**
     * The average disk transfer rate (megabytes per second).
     */
    final public double transferRate;

    /**
     * 
     * @param seekTime
     *            The average disk seek time (milliseconds).
     * @param transferRate
     *            The average disk transfer rate (megabytes per second).
     */
    public DiskCostModel(double seekTime, double transferRate) {

        this.seekTime = seekTime;

        this.transferRate = transferRate;

    }

}