Allocation of objects

[SAUDUBRAY, Fabien]

Thanks for your help ! 

I have still 2 questions :
1) I see in Changelog that why the Mega patch of 2002-07-01 "it appears that
the name_table field is no longer needed."
I try to find any usage of this name_table but it really seams that this
table is not used.
Yet the field remains and memory is still allocated for this fiels in
_Objects_Extend_information. Why keeping an unused field and doing
unnecessary job ?

2) Why keeping the Inactive_List mechanism in the unlimited case ? I means
that in this unlimited case execution time for _Object_Allocate function is
no longer determinist because it depends if the Inactive List is empty or
not.
I mean that we could just allocate a new entry in the local_table field, and
allocate the memory for one object control block.  


-----Original Message-----
From: Chris Johns [mailto:chrisj at rtems.org] 
Sent: Wednesday, May 18, 2005 2:41 PM
To: SAUDUBRAY, Fabien
Cc: 'rtems-users at rtems.com'
Subject: Re: Allocation of objects


SAUDUBRAY, Fabien wrote:
> I'm not sure of my understanding :
> 
> Memory for objects is reserved, but is memory for objects  allocated 
> during Initialization. (ie during _Objects_Initialize_information calls ?
)
> 
> Because when we create an object (a task for example), the kernel calls 
> the _Object_Allocate directive which returns the first object in the 
> Inactive Chain of this kind of Object. But this implies that this Chain 
> had been allocated before ?
> 

Originally the configuration table defined the number of objects for 
each type. The "unlimited" flag was introduced that allowed the number 
of objects to grow.

A static number of objects gives a fixed deterministic time to create a 
resource such as a task. The unlimited flag turns the configuration 
table value into a block size. This lets you control the amount of 
workspace overhead you get when the object table grows or shrinks. You 
how-ever need to size the workspace to meet your needs.

You can find more details about the unlimited flag and sizing the 
workspace here:

http://www.rtems.org/onlinedocs/releases/rtemsdocs-4.6.2/share/rtems/html/c_
user/c_user00386.html

  [ The auto-extending mode can .... ]

and a little about how it works here:

  http://www.rtems.org/ml/rtems-users/2005/april/msg00054.html

-- 
  Chris Johns
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