Hallo,

attached you will find the results of Xemonai latency measurements on
various embedded PowerPC boards using MPC 8xx and AMCC 4xx processors,
from low to high end covering a worst case latency range from 25 to 225
us. It also includes a comparison with RTAI 3.0r5 on the slowest CPU.
Here are some remarks and comments:

- On low-end processor code size matters a lot and it's difficult to
  beat RTAI/RTHAL.

- Apart from the CPU power, big caches and a fast memory interface
  improves latencies.

- L2 cache improves latencies a lot (compare Ocotea with Yosemite).

- I'm a bit puzzled about the results of the "cruncher" test. Could
  someone explain the output, please?

- Stability seems already quite good. At least I did not observe any
  crash yet :-).

The PowerPC port of Xenomai is already in good shape. That's great!

Wolfgang.



Latency tests with Xenomai on various PowerPC boards
----------------------------------------------------

Board   : Processor  CPU-Clk Bus-Clk I-Cache D-Cache Memory Remarks

TQM860L : MPC 860     50 MHz  50 MHz    4 KB    4 kB  16 MB
TQM866M : MPC 866    133 MHz  66 MHz   16 KB    8 kB 128 MB

Walnut  : AMCC 405GP 200 MHz 100 MHz   16 KB    8 kB  32 MB
Yosemite: AMCC 440EP 533 MHz 133 MHz   32 KB   32 KB 256 MB DDR-RAM, FPU
Ocotea  : AMCC 440GX 533 MHz 152 MHz   32 KB   32 KB 256 MB DDR-RAM, L2 256 KB


Linux  : DENX linux-2.6.14-rc3-g4c234921
iPipe  : 1.0-00
Xenomai: SVN 2005-10-15


CRUNCER without load:

         | Ideal computation time
TQM860L  |   368 us ???
TQM866L  | 10008 us 
Walnut   | 10150 us
Yosemite |  9911 us
Ocotea   |  9479 us 


SWITCH without load:

         |     lat min|     lat avg|     lat max|        lost
TQM860L  |      103360|      107840|      209280|           0
TQM866L  |       25745|       31880|       51369|           5
Walnut   |       24620|       25965|       32280|           1
Yosemite |        5626|        5655|       17403|           0
Ocotea   |        5158|        5169|       10038|           0


KLATENCY with load:

         |-----lat min|-----lat avg|-----lat max|-overrun|---test-time
TQM860L  |       50560|       98976|      199040|       0|    00:09:45
TQM866L  |       13835|       28571|       74348|       0|    00:11:44
Walnut   |       16195|       25062|       45755|       0|    00:10:09
Yosemite |        3106|        9697|       36832|       0|    00:09:55
Ocotea   |        3575|        7438|       24474|       0|    00:10:50


LATENCY with load:

         |-----lat min|-----lat avg|-----lat max|-overrun|---test-time
TQM860L  |       60480|      120960|      224320|       0|    00:09:46
TQM866L  |       15759|       34286|       78799|       0|    00:11:14
Walnut   |       21070|       31650|       64500|       0|    00:09:58
Yosemite |        3808|       12163|       47898|       0|    00:10:00
Ocotea   |        3575|        7438|       24474|       0|    00:10:50


KLATENCY comparison Xenomai 2.0 vs. RTAI/RTHAL 3.0r5 on TQM860L:
---------------------------------------------------------------

KLATENCY with load:

            |-----lat min|-----lat avg|-----lat max|-overrun|---test-time
Xenomai 2.0 |       50560|       98976|      199040|       0|    00:09:45
RTAI 3.0r5  |       23120|       31838|       70520|       ?|    00:12:26



Note: load has been put onto the system by running in a telnet session
      "ping -f <remote-host-ip>" and "while ls; do ls; done".

Note: all test have been run with CONFIG_XENO_HW_TIMER_LATENCY="1" and
      CONFIG_XENO_HW_SCHED_LATENCY="1" to get correct latancy values.
      RTAI figures have been corrected manually.


Attachment: xenomai-latencies-ppc.tgz
Description: GNU Zip compressed data

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