[cadynce] On being able to pace periodic application strings... (Comparing Linux 2.6.9 and 2.6.20-rt8)

[Gautam Thaker]

James Hill wrote:
> Hey Gautam, 
> 
> 
>>-----Original Message-----
>>From: cadynce-bounces at list.isis.vanderbilt.edu 
>>[mailto:cadynce-bounces at list.isis.vanderbilt.edu] On Behalf 
>>Of Gautam Thaker
>>Sent: Thursday, May 10, 2007 12:34 PM
>>To: cadynce at list.isis.vanderbilt.edu
>>Subject: [cadynce] On being able to pace periodic application 
>>strings... (Comparing Linux 2.6.9 and 2.6.20-rt8)
>>
>>Hi Adam, Raytheon and James, (and others):
>>
>>One thing you may want to be careful of is how you actual 
>>subject the application strings to the update rates that you 
>>want. 
> 
> 
> Maybe I missed something, but who said we are makin changes to the
> workloads??
> 
> Thanks,
> 
> James
> 
HI James:

Sorry for any confusion, by "update rates" I did not mean "change rates that we have been using", 
but simply I meant the "arrival rate" ( in msgs/sec) that is listed in the workload description. 
What I am suggesting is that you may want to carefully measure if indeed you are getting the arrival 
rate these workloads are asking for since having accurate arrival rates will let you have confidence 
  is what gets measured.

Hope I am a bit more clear this time.

Gautam

> 
>>If one looks at message arrival rates in:
>>
>>https://escher.isis.vanderbilt.edu/twiki/pub/CADYNCE/OneFiftyF
>>iftyCase1/WorkloadDescription.htm
>>
>>one observes that there are some non well-rounded values for 
>>message rates. In any event, one wants to have good control 
>>over rate at which we inject messages into our experiments. 
>>In our tests ultimately we rely on 'nanosleep()' to 
>>accurately pace our message rates. (this or similar must be 
>>what CUTS based models use, James?) Please see the following 
>>link that shows if you use non-RT Linux kernel you may get 
>>some strange results. It is for this reason, among others, 
>>that  we test w/ RT Linux. 
>>PoR is also  using RT Linux.
>>
>>http://www.atl.external.lmco.com/projects/QoS/RTOS_html/timer_
>>gran/linux_2.6.9_and_2.6.20-rt8_compared.html
>>
>>Gautam
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