bdbuf.h

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/*
 * Copyright (C) 2001 OKTET Ltd., St.-Petersburg, Russia
 * Author: Victor V. Vengerov <vvv@oktet.ru>
 *
 * Copyright (C) 2008,2009 Chris Johns <chrisj@rtems.org>
 *    Rewritten to remove score mutex access. Fixes many performance
 *    issues.
 *    Change to support demand driven variable buffer sizes.
 *
 * Copyright (c) 2009-2012 embedded brains GmbH.
 */

#ifndef _RTEMS_BDBUF_H
#define _RTEMS_BDBUF_H

#include <rtems.h>
#include <rtems/libio.h>
#include <rtems/chain.h>

#include <rtems/blkdev.h>
#include <rtems/diskdevs.h>

#ifdef __cplusplus
extern "C" {
#endif

#if defined(RTEMS_POSIX_API)
  /*
   * Use the PTHREAD mutexes and condition variables if available.  This helps
   * on SMP configurations to avoid the home grown condition variables via
   * disabled preemption.
   */
  #define RTEMS_BDBUF_USE_PTHREAD
#endif

typedef enum
{
  RTEMS_BDBUF_STATE_FREE = 0,

  RTEMS_BDBUF_STATE_EMPTY,

  RTEMS_BDBUF_STATE_CACHED,

  RTEMS_BDBUF_STATE_ACCESS_CACHED,

  RTEMS_BDBUF_STATE_ACCESS_MODIFIED,

  RTEMS_BDBUF_STATE_ACCESS_EMPTY,

  RTEMS_BDBUF_STATE_ACCESS_PURGED,

  RTEMS_BDBUF_STATE_MODIFIED,

  RTEMS_BDBUF_STATE_SYNC,

  RTEMS_BDBUF_STATE_TRANSFER,

  RTEMS_BDBUF_STATE_TRANSFER_PURGED
} rtems_bdbuf_buf_state;

struct rtems_bdbuf_group;
typedef struct rtems_bdbuf_group rtems_bdbuf_group;

typedef struct rtems_bdbuf_buffer
{
  rtems_chain_node link;       
  struct rtems_bdbuf_avl_node
  {
    struct rtems_bdbuf_buffer* left;   
    struct rtems_bdbuf_buffer* right;  
    signed char                cache;  
    signed char                bal;    
  } avl;

  rtems_disk_device *dd;        
  rtems_blkdev_bnum block;      
  unsigned char*    buffer;     
  rtems_bdbuf_buf_state state;           
  uint32_t waiters;              
  rtems_bdbuf_group* group;      
  uint32_t hold_timer;           
  int   references;              
  void* user;                    
} rtems_bdbuf_buffer;

struct rtems_bdbuf_group
{
  rtems_chain_node    link;          
  size_t              bds_per_group; 
  uint32_t            users;         
  rtems_bdbuf_buffer* bdbuf;         
};

typedef struct rtems_bdbuf_config {
  uint32_t            max_read_ahead_blocks;   
  uint32_t            max_write_blocks;        
  rtems_task_priority swapout_priority;        
  uint32_t            swapout_period;          
  uint32_t            swap_block_hold;         
  size_t              swapout_workers;         
  rtems_task_priority swapout_worker_priority; 
  size_t              task_stack_size;         
  size_t              size;                    
  uint32_t            buffer_min;              
  uint32_t            buffer_max;              
  rtems_task_priority read_ahead_priority;     
} rtems_bdbuf_config;

extern const rtems_bdbuf_config rtems_bdbuf_configuration;

#define RTEMS_BDBUF_MAX_READ_AHEAD_BLOCKS_DEFAULT    0

#define RTEMS_BDBUF_MAX_WRITE_BLOCKS_DEFAULT         16

#define RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT    15

#define RTEMS_BDBUF_SWAPOUT_TASK_SWAP_PERIOD_DEFAULT 250

#define RTEMS_BDBUF_SWAPOUT_TASK_BLOCK_HOLD_DEFAULT  1000

#define RTEMS_BDBUF_SWAPOUT_WORKER_TASKS_DEFAULT     0

#define RTEMS_BDBUF_SWAPOUT_WORKER_TASK_PRIORITY_DEFAULT \
                             RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT

#define RTEMS_BDBUF_READ_AHEAD_TASK_PRIORITY_DEFAULT \
  RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT

#define RTEMS_BDBUF_TASK_STACK_SIZE_DEFAULT RTEMS_MINIMUM_STACK_SIZE

#define RTEMS_BDBUF_CACHE_MEMORY_SIZE_DEFAULT (64 * 512)

#define RTEMS_BDBUF_BUFFER_MIN_SIZE_DEFAULT (512)

#define RTEMS_BDBUF_BUFFER_MAX_SIZE_DEFAULT (4096)

rtems_status_code
rtems_bdbuf_init (void);

rtems_status_code
rtems_bdbuf_get (
  rtems_disk_device *dd,
  rtems_blkdev_bnum block,
  rtems_bdbuf_buffer** bd
);

rtems_status_code
rtems_bdbuf_read (
  rtems_disk_device *dd,
  rtems_blkdev_bnum block,
  rtems_bdbuf_buffer** bd
);

rtems_status_code
rtems_bdbuf_release (rtems_bdbuf_buffer* bd);

rtems_status_code
rtems_bdbuf_release_modified (rtems_bdbuf_buffer* bd);

rtems_status_code
rtems_bdbuf_sync (rtems_bdbuf_buffer* bd);

rtems_status_code
rtems_bdbuf_syncdev (rtems_disk_device *dd);

void
rtems_bdbuf_purge_dev (rtems_disk_device *dd);

rtems_status_code
rtems_bdbuf_set_block_size (rtems_disk_device *dd,
                            uint32_t           block_size,
                            bool               sync);

void
rtems_bdbuf_get_device_stats (const rtems_disk_device *dd,
                              rtems_blkdev_stats      *stats);

void
rtems_bdbuf_reset_device_stats (rtems_disk_device *dd);

#ifdef __cplusplus
}
#endif

#endif