RTEMS mvme5500 bsp

[Kate Feng]

Robert Varner wrote:

>
> Thank you for your help last week in understanding interrupts in RTEMS
>
> on the MVME5500.  With your suggestions and a little conceptual break
> through we have VME interrupts working well.
>
> Have you or anyone you know of made benchmarks of the performance of
> RTEMS on the MVME5500?  Particularly, we would like to know enough to
> judge which services to use and the time required for various context
> switches.
>
> Robert Varner
> ORNL Physics Division

I finally got around to  optimize the IRQ handling and
prioritization.  Many thanks to Till Straumann of SLAC
for  providing  some  suggestions. I modified (for  MVME5500)
the  latency benchmark  software which Till  posted
on http://www.slac.stanford.edu/~strauman/rtoslat/


The test was performed on the MVME5500 board.  2,000,000
timer interrupts were generated at a  rate of  4KHZ.  The
maximum and average  letencies for both the  idle and loaded
system were measured.   The loaded system was subject to heavy
network and console activities.  Please note that the worst case
(e.g. maximum) is  critical  for a real-time system.


The result is  listed below.  Based on the new algorithm, the result
for a VME interrupt in RTEMS should be very close to what is listed
as long as it's set at the highest priority  in irq_init.c.   Please let
me
know otherwise.  Any suggestions or  comments before I submitted
the patch ?    Also, the updated software fixed the  bug of
the irq->on() API, which was reported back in Feb..   -- Kate

______________________________________________________
MVME5500    Interrupt   Latency    |   Context Switching
_________________________________________________________
                           max      (average)   |     max    (average)
_________________________________________________________
Idle System:                                      |

RTEMS          5.04       (3.45)           |    6.80     (0.96)

vxWorks       12.13       (1.58)          |   18.68     (0.91)

_________________________________________________________
Loaded System:

RTEMS          8.17       (3.74)          |   24.88     (1.69)

vxWorks       22.49       (2.04)         |   40.76     (4.1)
_________________________________________________________

** All units are in usec.