[LITMUS^RT] litmus-dev Digest, Vol 81, Issue 3

[Björn Brandenburg]

Hi Ricardo,

> On 15. May 2019, at 02:44, Ricardo Teixeira <ricardo.btxr at gmail.com> wrote:
> 
>> Below are the kernel messages for the overhead and schedule tracers.

these messages look reasonable; I don’t see anything suggesting that there might be a problem. 

>> When I'm looking for UNLOCK events through ftdump, I noticed that almost all UNLOCK_START records are generated with IRQ enabled for both protocols I'm running.

What do you mean with “almost all [...] with IRQ enabled”? Do you have different lock entry paths, some with IRQs enabled and some without? 

Or do you mean the IRQ field in the trace records? That’s a snapshot of the core’s IRQ *counter*, which is reset when it is read. It’s perfectly normal for this number to be non-zero for a _START event — on average, you’d expect there to have been some interrupts since the last time that an event was recorded. 

>> Is this why these records are not being counted? Is there any parameter so I can collect these records? 

Yes, -x disables interrupt filtering, but, again, this should not be an issue for _START events. 

https://github.com/LITMUS-RT/feather-trace-tools/blob/master/src/ft2csv.c#L397

You had mentioned in some email that you use “inherited” scripts that produce a single .ft file — I have no idea what these scripts are, where they come from, or what they do, so I can’t really help you debug them. I would recommend to use the standard tools as described in the tutorial. 

https://github.com/LITMUS-RT/feather-trace-tools/blob/master/doc/howto-trace-and-process-overheads.md

At the very least, see if the problem persists if you follow that approach. 

Regards,
Björn


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