Lower defaults in confdefs.h

[Joel Sherrill]

There was only one reply to this.  It indicated that 
doing this was a good thing.  So this is going to get
done before the next beta.  Be warned!!!
 
   IF YOUR APPLICATION DEPENDS ON THE DEFAULT 
   NUMBER OF TASKS/THREADS BEING 10 TO RUN, THEN 
   IT WILL FAIL BEGINNING WITH THE NEXT BETA!!!

A quick spot check shows that in debug mode, hello_g.exe
for the sparc/erc32 ended up with a work_space_size 
configured as 183,296 but 129,800 was never used.  That
is slightly above the amount of memory required by 29
task stacks (9 Classic, 10 pthreads, and 10 ITRON) that
the default reserved memory for.


Joel Sherrill wrote:
 
> I have been mulling over lowering some of the default values
> in confdefs.h to reduce executive workspace size.  In particular,
> these default too high for most applications:
> 
> CONFIGURE_MAXIMUM_TASKS - Classic API tasks defaults to 10
> CONFIGURE_MAXIMUM_POSIX_THREADS - POSIX threads defaults to
>   10 when POSIX API is enabled
> CONFIGURE_MAXIMUM_ITRON_TASKS - ITRON tasks defaults to
>   10 when ITRON API is enabled
> CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS is the number of
>   file descriptors and defaults to 20.
> 
> Remember each task configured results in stack space
> being reserved so 30 tasks can be a LOT of memory.
> I think the defaults for tasks/threads should be 0 thus
> forcing the application to specify an appropriate number.
> 
> I think the default number of file descriptors should
> be 3 to support stdin, stdout, and stderr.
> 
> I am also open to discussion as to whether
> CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM should be the default.
> This reduces the functionality of the IMFS to be comparable
> to the functionality in version 4.0 -- device nodes.
> 
> I bring this up now because if the defaults are to change it
> should happen before a major release to avoid getting more
> applications dependent on the higher defaults.
> 
> Comments appreciated.
> 
> --
> Joel Sherrill, Ph.D.             Director of Research & Development
> joel at OARcorp.com                 On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>    Support Available             (256) 722-9985

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985