[ag-automation] some stresstest results with Xenomai and Preempt-RT

[Wolfgang Grandegger]

Wolfgang Grandegger wrote:
> Hello,
> 
> I'm trying to do similar test for the PowerPC Ocotea board. I was able 
> to build and boot a RT-preempt kernel 2.6.16-rt13 (plus the patch at 
> http://marc.theaimsgroup.com/?l=linux-kernel&m=114443684122525&w=2) for 
> the Ocotea board and run cyclictest but I'm puzzled about the results. 
> Without "-s" I get wired high latency figures increasing constantly over 
> time. With "-s" I got under load (cache calibrator + ping flood):
> 
>   bash-3.00# ./cyclictest -n -s -c 1
>   2.33 1.49 0.81 2/41 11245
> 
>   T: 0 (26879) P: 0 I:    1000 C: 97441 0 Min: 1333 Act: 3021 Max: 4736
> 
> I assume these numbers are "micro-seconds" but then 4.7 ms is a lot. 
> Well, I'm not sure if RT preempt works properly. Maybe somebody could help.

I think I found the problem. HIGH_RES_TIMERS are not supported for PPC 
(arch/ppc) but PowerPC (arch/powerpc). Unfortunately, most embedded 
PowerPC boards are not yet supported by the new PowerPC tree (unifying 
32- and 64-bit PowerPC archs).

Wolfgang.

> Thanks.
> 
> Wolfgang.
> 
> Luotao Fu wrote:
>> Hi folks,
>> I'm following the example of ealier threads and thus open this thread in
>> english :-) I did some Stresstest with Pr-RT and Xenomai, in the
>> following some simple results for evtl. further discussion:
>>
>> Testcandidate:
>> A: Preempt-RT 2.6.16-rt16
>> B: Xenomai (svn Rev. #949)
>>
>> Hardware:
>> Intel Celeron 733MHz, 256 MB RAM, no SWAP.
>> Testtools:
>> * Cyclictest (originally by tglx, modified by Jan Kiszka, available at
>>   the svn trunk of the xenomai project)
>> * irLat (interrupt latency tool, based on the concept of LPPTEST by tglx,
>> we'll release the tool soon)
>>
>> used libraries/skins:
>> A: NPTL
>> B: POSIX Skin, RTDM Skin
>>
>> (non-realtime) Workload:
>> * cache calibrator (http://monetdb.cwi.nl/Calibrator/)
>> * flood ping
>>
>> Test duration:
>> about 5 hours each
>>
>> Results:
>> * irLat:
>>   |  Min(usec)  |  Max(usec)  A |  3.1985     |  105.33 B |  
>> 3.2130     |  92.52
>> **********************************
>>
>> * cyclictest:
>> A:
>> root at krachkiste:/ptx/work/lfu/utils/cyclictest ./cyclictest -p 80 -t 5 -n
>> 1.58 1.61 1.62 3/68 4079
>>
>> T: 0 ( 3131) P:80 I:    1000 C:16469865 Min:       8 Act:      35 Max: 
>> 192
>> T: 1 ( 3132) P:79 I:    1500 C: 9979903 Min:       8 Act:      34 Max: 
>> 215
>> T: 2 ( 3133) P:78 I:    2000 C: 7934887 Min:       9 Act:      38 Max: 
>> 123
>> T: 3 ( 3134) P:77 I:    2500 C: 6587910 Min:       9 Act:      35 Max: 
>> 161
>> T: 4 ( 3135) P:76 I:    3000 C: 5489925 Min:       9 Act:      57 Max: 
>> 186
>> ______________________________________
>>
>> B:
>> root at krachkiste:/ptx/work/lfu/local/xenomai/testsuite/cyclic 
>> ./cyclictest -n -p 80 -t 5
>> 1.16 1.05 1.01 2/43 4063
>>
>> T: 0 ( 3381) P:80 I:    1000 C:17461866 Min:       1 Act:       7 Max: 
>> 151
>> T: 1 ( 3382) P:79 I:    1500 C:11641244 Min:       1 Act:       7 Max: 
>> 223
>> T: 2 ( 3383) P:78 I:    2000 C: 8730933 Min:       1 Act:      10 Max: 
>> 125
>> T: 3 ( 3384) P:77 I:    2500 C: 6984747 Min:       1 Act:      10 Max: 
>> 134
>> T: 4 ( 3385) P:76 I:    3000 C: 5820622 Min:       1 Act:       8 Max: 99
>>
>>
>> Both systems show reliable results under heavy cache and interrupt 
>> workload. Though the extreme values of testresults are quite near to 
>> each other,
>> both candidates show quite different behaviour during the test. The
>> presented results are just simple final results, in case
>> of interest we'll post later some more detailed informations like plots,
>> results of tracing/profiling, results of further benchmark tools etc.
>>
>> P.S. The Kernelconfiguration of both candidates are mostly identical.
>> The configfiles, together with a list of running processes, are attached
>> to this mail.
>>
>> Cheers
>> Luotao Fu
>>
>>
>> ------------------------------------------------------------------------
>>
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