Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 29 Sep 2010 12:15:50 -0500

On Wednesday 29 September 2010 11:15:25 Eric Norum wrote:
>
> How long has it been since someone actually tested vxWorks to see if it
> still exhibit this fragmentation issue? Sometimes urban legends are just
> that.

It seems that vxWorks 6.8 does use a best-fit algorithm for memory allocation, 
with both the Kernel and RTP APIs.  However the vxWorks 5.5.x routines still 
use first-fit, which is what causes the fragmentation to occur.  We might be 
able to insist on vxWorks 6.x with future R3.15.x releases of Base, but even 
there I think there might be some wailing and gnashing of teeth...

> > Alternatively we could add integer literal support to the code in
> > libCom/calc, which would reduce the incremental expansion factor from
> > 21/4 to 10/3 or better, but again that would be making code changes
> > uncomfortably late in the development cycle for 3.14.12.
>
> Are the changes that extensive?

I haven't written then yet, and I don't know if I'll have time in the next 
week or so.  They are all localized within libCom/calc though, and there's a 
pretty good unit test program now (which would also need updating BTW).

- Andrew
-- 
If a man is offered a fact which goes against his instincts, he will
scrutinize it closely, and unless the evidence is overwhelming, he will
refuse to believe it.  If, on the other hand, he is offered something
which affords a reason for acting in accordance to his instincts, he
will accept it even on the slightest evidence.  -- Bertrand Russell

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System