Return to rf_cvscan.h CVS log

Up to [local] / sys / dev / raidframe

Annotation of sys/dev/raidframe/rf_cvscan.h, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: rf_cvscan.h,v 1.3 2002/12/16 07:01:03 tdeval Exp $    */
                      2: /*     $NetBSD: rf_cvscan.h,v 1.3 1999/02/05 00:06:07 oster Exp $      */
                      3:
                      4: /*
                      5:  * Copyright (c) 1995 Carnegie-Mellon University.
                      6:  * All rights reserved.
                      7:  *
                      8:  * Author: Mark Holland
                      9:  *
                     10:  * Permission to use, copy, modify and distribute this software and
                     11:  * its documentation is hereby granted, provided that both the copyright
                     12:  * notice and this permission notice appear in all copies of the
                     13:  * software, derivative works or modified versions, and any portions
                     14:  * thereof, and that both notices appear in supporting documentation.
                     15:  *
                     16:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
                     17:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
                     18:  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
                     19:  *
                     20:  * Carnegie Mellon requests users of this software to return to
                     21:  *
                     22:  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
                     23:  *  School of Computer Science
                     24:  *  Carnegie Mellon University
                     25:  *  Pittsburgh PA 15213-3890
                     26:  *
                     27:  * any improvements or extensions that they make and grant Carnegie the
                     28:  * rights to redistribute these changes.
                     29:  */
                     30:
                     31: /*
                     32:  *     Disk scheduling by CVSCAN( N, r )
                     33:  *
                     34:  *     Given a set of requests, partition them into one set on each
                     35:  *     side of the current arm position.  The trick is to pick which
                     36:  *     side you are going to service next; once a side is picked you will
                     37:  *     service the closest request.
                     38:  *     Let there be n1 requests on one side and n2 requests on the other
                     39:  *     side.  If one of n1 or n2 is zero, select the other side.
                     40:  *     If both n1 and n2 are nonzero, select a "range" for examination
                     41:  *     that is N' = min( n1, n2, N ).  Average the distance from the
                     42:  *     current position to the nearest N' requests on each side giving
                     43:  *     d1 and d2.
                     44:  *     Suppose the last decision was to move toward set 2, then the
                     45:  *     current direction is toward set 2, and you will only switch to set
                     46:  *     1 if d1+R < d2 where R is r*(total number of cylinders), r in [0,1].
                     47:  *
                     48:  *     I extend this by applying only to the set of requests that all
                     49:  *     share the same, highest priority level.
                     50:  */
                     51:
                     52: #ifndef        _RF__RF_CVSCAN_H_
                     53: #define        _RF__RF_CVSCAN_H_
                     54:
                     55: #include "rf_diskqueue.h"
                     56:
                     57: typedef enum RF_CvscanArmDir_e {
                     58:        rf_cvscan_LEFT,
                     59:        rf_cvscan_RIGHT
                     60: } RF_CvscanArmDir_t;
                     61:
                     62: typedef struct RF_CvscanHeader_s {
                     63:        long                     range_for_avg;         /* CVSCAN param N */
                     64:        long                     change_penalty;        /* CVSCAN param R */
                     65:        RF_CvscanArmDir_t        direction;
                     66:        RF_SectorNum_t           cur_block;
                     67:        int                      nxt_priority;
                     68:        RF_DiskQueueData_t      *left;
                     69:        int                      left_cnt;
                     70:        RF_DiskQueueData_t      *right;
                     71:        int                      right_cnt;
                     72:        RF_DiskQueueData_t      *burner;
                     73: } RF_CvscanHeader_t;
                     74:
                     75: int   rf_CvscanConfigure(void);
                     76: void *rf_CvscanCreate(RF_SectorCount_t, RF_AllocListElem_t *,
                     77:        RF_ShutdownList_t **);
                     78: void  rf_CvscanEnqueue(void *, RF_DiskQueueData_t *, int);
                     79: RF_DiskQueueData_t *rf_CvscanDequeue(void *);
                     80: RF_DiskQueueData_t *rf_CvscanPeek(void *);
                     81: int   rf_CvscanPromote(void *, RF_StripeNum_t, RF_ReconUnitNum_t);
                     82:
                     83: #endif /* !_RF__RF_CVSCAN_H_ */