Changeset 338502f in rtems


Ignore:
Timestamp:
Apr 19, 1999, 5:40:20 PM (22 years ago)
Author:
Joel Sherrill <joel.sherrill@…>
Branches:
4.10, 4.11, 4.8, 4.9, 5, master
Children:
c2463d9
Parents:
b56206a
Message:

Unlimited objects information from Chris Johns (ccj@…).

File:
1 edited

Legend:

Unmodified
Added
Removed
  • doc/user/conf.t

    rb56206a r338502f  
    935935@code{@value{RPREFIX}INVALID_ADDRESS} error code.
    936936
    937 A worksheet is provided in the Memory Requirements
     937A worksheet is provided in the @b{Memory Requirements}
    938938chapter of the Applications Supplement document for a specific
    939939target processor to assist the user in calculating the minimum
    940940size of the RTEMS RAM Workspace for each application.  The value
    941941calculated with this worksheet is the minimum value that should
    942 be specified as the work_space_size parameter of the
    943 Configuration Table.  The user is cautioned that future versions
    944 of RTEMS may not have the same memory requirements per object.
    945 Although the value calculated is sufficient for a particular
    946 target processor and release of RTEMS, memory usage is subject
    947 to change across versions and target processors.  The user is
    948 advised to allocate somewhat more memory than the worksheet
    949 recommends to insure compatibility with future releases for a
    950 specific target processor and other target processors.  To avoid
    951 problems, the user should recalculate the memory requirements
    952 each time one of the following events occurs:
     942be specified as the @code{work_space_size} parameter of the
     943Configuration Table. 
     944
     945The allocation of objects can operate in two modes. The default mode
     946has an object number ceiling. No more than the specified number of
     947objects can be allocated from the RTEMS RAM Workspace. The number of objects
     948specified in the particular API Configuration table fields are
     949allocated at initialisation. The second mode allows the number of
     950objects to grow to use the available free memory in the RTEMS RAM Workspace.
     951
     952The auto-extending mode can be enabled individually for each object
     953type by using the macro @code{rtems_resource_unlimited}. This takes a value
     954as a parameter, and is used to set the object maximum number field in
     955an API Configuration table. The value is an allocation unit size. When
     956RTEMS is required to grow the object table it is grown by this
     957size. The kernel will return the object memory back to the RTEMS RAM Workspace
     958when an object is destroyed. The kernel will only return an allocated
     959block of objects to the RTEMS RAM Workspace if at least half the allocation
     960size of free objects remain allocated. RTEMS always keeps one
     961allocation block of objects allocated. Here is an example of using
     962@code{rtems_resource_unlimited}:
     963
     964@example
     965#define CONFIGURE_MAXIMUM_TASKS rtems_resource_unlimited(5)
     966@end example
     967
     968The user is cautioned that future versions of RTEMS may not have the
     969same memory requirements per object. Although the value calculated is
     970suficient for a particular target processor and release of RTEMS,
     971memory usage is subject to change across versions and target
     972processors.  The user is advised to allocate somewhat more memory than
     973the worksheet recommends to insure compatibility with future releases
     974for a specific target processor and other target processors. To avoid
     975problems, the user should recalculate the memory requirements each
     976time one of the following events occurs:
    953977
    954978@itemize @bullet
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