[comp.realtime] VxWorks Performance Data

cioli@savax.UUCP (Jeff J. Cioli) (11/22/89)

Does anyone have any performance data (e.g. benchmarks results, papers) con-
cerning context switch, interrupt latency, message delivery latency, etc for
VxWorks and the various underlying kernels ?

Thanks

wbrown@beva.bev.lbl.gov (Bill Brown) (11/27/89)

In article <1081@savax.UUCP> cioli@savax.UUCP (Jeff J. Cioli) writes:
>Does anyone have any performance data (e.g. benchmarks results, papers) con-
>cerning context switch, interrupt latency, message delivery latency, etc for
>VxWorks and the various underlying kernels ?
>
>Thanks

							 ____
							|    |____|

							|    |
							|    |
							Time
							Between
							Writes
								Square wave
								Frequency

MVME-147
	Square-wave
		Direct write*				2 uS.
								250 KHz.
		
		Function Call*				5 uS
								100 KHz




MVME-133 {CMC E-net, MVME-025 VME Controller}
	Square-wave
	    
		Direct Write*				3 uS.
								167 KHz.

		Function Call*				8.5 uS.
								118 Khz.

		RPC					xx Ms.
								xx Hz.


	* Output device is ACROMAG 9210 D.A.C. board

I also made a couple of interrupt-latency checks - as best I can recall
it's about 15 microseconds between the interrupt on the VME bus and
the first instruction in the interrupt function.  This was probably
using a '147 board (naw - I don't gotta write it down - I can remember
it when I need it).  We are using the Wind kernel.

I believe that a task switch takes on the order of couple of hundred
microseconds but don't have any hard figures.  

It would be possible to cut down the interrupt latency a little bit by
doing some assembly language stuff, rather than using vxWorks'
intConnect() but the gain is not much, a say less than a factor of 2.

I hope this helps - it's not everything you asked for, but at least it's
something.

						-bill
						wlbrown@lbl.gov

Disclaimer:  These opinions are my own and have nothing to do with the
    official policy or management of L.B.L, who probably couldn't care 
    less about employees who play with trains.

sccowan@watmsg.waterloo.edu (S. Crispin Cowan) (11/29/89)

In article <4295@helios.ee.lbl.gov> wbrown@beva.bev.lbl.gov (Bill Brown) writes:
>In article <1081@savax.UUCP> cioli@savax.UUCP (Jeff J. Cioli) writes:
>>Does anyone have any performance data (e.g. benchmarks results, papers) con-
>>cerning context switch, interrupt latency, message delivery latency, etc for
>>VxWorks and the various underlying kernels ?
>>
>>Thanks
>MVME-133 {CMC E-net, MVME-025 VME Controller}
>	Square-wave
>	    
>		Direct Write*				3 uS.
>								167 KHz.
>		RPC					xx Ms.
>								xx Hz.
I would really like to see the RPC figure, if anyone has it.  Also,
any of the context-switching figures mentioned in the first message
would be appreciated.

>						-bill
>						wlbrown@lbl.gov
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