RTEMS 6.1-rc5
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Macros
Block Device Cache Configuration
API » Application Configuration Options

Macros

#define CONFIGURE_APPLICATION_NEEDS_LIBBLOCK
 This configuration option is a boolean feature define.
 
#define CONFIGURE_BDBUF_BUFFER_MAX_SIZE
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_BUFFER_MIN_SIZE
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_CACHE_MEMORY_SIZE
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_MAX_READ_AHEAD_BLOCKS
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_MAX_WRITE_BLOCKS
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_READ_AHEAD_TASK_PRIORITY
 This configuration option is an integer define.
 
#define CONFIGURE_BDBUF_TASK_STACK_SIZE
 This configuration option is an integer define.
 
#define CONFIGURE_SWAPOUT_BLOCK_HOLD
 This configuration option is an integer define.
 
#define CONFIGURE_SWAPOUT_SWAP_PERIOD
 This configuration option is an integer define.
 
#define CONFIGURE_SWAPOUT_TASK_PRIORITY
 This configuration option is an integer define.
 
#define CONFIGURE_SWAPOUT_WORKER_TASKS
 This configuration option is an integer define.
 
#define CONFIGURE_SWAPOUT_WORKER_TASK_PRIORITY
 This configuration option is an integer define.
 

Detailed Description

This section describes configuration options related to the Block Device Cache (bdbuf).

Macro Definition Documentation

◆ CONFIGURE_APPLICATION_NEEDS_LIBBLOCK

#define CONFIGURE_APPLICATION_NEEDS_LIBBLOCK

This configuration option is a boolean feature define.

In case this configuration option is defined, then the Block Device Cache is initialized during system initialization.

Default Configuration
If this configuration option is undefined, then the described feature is not enabled.
Notes
Each option of the Block Device Cache (bdbuf) configuration can be explicitly set by the user with the configuration options below. The Block Device Cache is used for example by the RFS and DOSFS filesystems.

◆ CONFIGURE_BDBUF_BUFFER_MAX_SIZE

#define CONFIGURE_BDBUF_BUFFER_MAX_SIZE

This configuration option is an integer define.

The value of this configuration option defines the maximum size of a buffer in bytes.

Default Value
The default value is 4096.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be an integral multiple of CONFIGURE_BDBUF_BUFFER_MIN_SIZE.

◆ CONFIGURE_BDBUF_BUFFER_MIN_SIZE

#define CONFIGURE_BDBUF_BUFFER_MIN_SIZE

This configuration option is an integer define.

The value of this configuration option defines the minimum size of a buffer in bytes.

Default Value
The default value is 512.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.

◆ CONFIGURE_BDBUF_CACHE_MEMORY_SIZE

#define CONFIGURE_BDBUF_CACHE_MEMORY_SIZE

This configuration option is an integer define.

The value of this configuration option defines the size of the cache memory in bytes.

Default Value
The default value is 32768.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to SIZE_MAX.

◆ CONFIGURE_BDBUF_MAX_READ_AHEAD_BLOCKS

#define CONFIGURE_BDBUF_MAX_READ_AHEAD_BLOCKS

This configuration option is an integer define.

The value of this configuration option defines the maximum blocks per read-ahead request.

Default Value
The default value is 0.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.
Notes
A value of 0 disables the read-ahead task (default). The read-ahead task will issue speculative read transfers if a sequential access pattern is detected. This can improve the performance on some systems.

◆ CONFIGURE_BDBUF_MAX_WRITE_BLOCKS

#define CONFIGURE_BDBUF_MAX_WRITE_BLOCKS

This configuration option is an integer define.

The value of this configuration option defines the maximum blocks per write request.

Default Value
The default value is 16.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.

◆ CONFIGURE_BDBUF_READ_AHEAD_TASK_PRIORITY

#define CONFIGURE_BDBUF_READ_AHEAD_TASK_PRIORITY

This configuration option is an integer define.

The value of this configuration option defines the read-ahead task priority.

Default Value
The default value is 15.
Constraints
The value of the configuration option shall be a valid Classic API task priority. The set of valid task priorities depends on the scheduler configuration.

◆ CONFIGURE_BDBUF_TASK_STACK_SIZE

#define CONFIGURE_BDBUF_TASK_STACK_SIZE

This configuration option is an integer define.

The value of this configuration option defines the task stack size of the Block Device Cache tasks in bytes.

Default Value
The default value is RTEMS_MINIMUM_STACK_SIZE.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to CONFIGURE_MINIMUM_TASK_STACK_SIZE.
  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.
  • The value of the configuration option shall be small enough so that the task stack space calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

◆ CONFIGURE_SWAPOUT_BLOCK_HOLD

#define CONFIGURE_SWAPOUT_BLOCK_HOLD

This configuration option is an integer define.

The value of this configuration option defines the swapout task maximum block hold time in milliseconds.

Default Value
The default value is 1000.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.

◆ CONFIGURE_SWAPOUT_SWAP_PERIOD

#define CONFIGURE_SWAPOUT_SWAP_PERIOD

This configuration option is an integer define.

The value of this configuration option defines the swapout task swap period in milliseconds.

Default Value
The default value is 250.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.

◆ CONFIGURE_SWAPOUT_TASK_PRIORITY

#define CONFIGURE_SWAPOUT_TASK_PRIORITY

This configuration option is an integer define.

The value of this configuration option defines the swapout task priority.

Default Value
The default value is 15.
Constraints
The value of the configuration option shall be a valid Classic API task priority. The set of valid task priorities depends on the scheduler configuration.

◆ CONFIGURE_SWAPOUT_WORKER_TASK_PRIORITY

#define CONFIGURE_SWAPOUT_WORKER_TASK_PRIORITY

This configuration option is an integer define.

The value of this configuration option defines the swapout worker task priority.

Default Value
The default value is 15.
Constraints
The value of the configuration option shall be a valid Classic API task priority. The set of valid task priorities depends on the scheduler configuration.

◆ CONFIGURE_SWAPOUT_WORKER_TASKS

#define CONFIGURE_SWAPOUT_WORKER_TASKS

This configuration option is an integer define.

The value of this configuration option defines the swapout worker task count.

Default Value
The default value is 0.
Constraints

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.
  • The value of the configuration option shall be less than or equal to UINT32_MAX.
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