my notes from the tracing workshop

[Andrew Cagney]

Frank Ch. Eigler wrote:
>> [...]
>> "DB"
>> There was a strong consensus that the "internal" format of the log
>> data needed to be a fast light weight database; two vendors were using
>> sqlite for instance (TPTP the eclipse tool didn't but I suspect will
>> shortly).  [...]
>>     
>
> This seems rather wacky.  If they're talking about gigabytes of trace
> traffic, a little wee in-memory database is a reach.  If you need to
> do declarative querying, then you need a real database with indexes
> and whatnot.  If you just need a big ass array, use BerkeleyDB.  If
> you just want strongly typed flat data on disk, go XML.  I wish I'd
> been there - perhaps my perceptions could have been falsified.
>
>   

Right, SqLite is a little wee in-process database;  it provides a 
mechanism for powerful queries without the overhead of a server 
implementation.  Wind River presented performance numbers supporting the 
approaches usability; in particular timing such as populating the 
database from trace logs.  While that cost is real, it is outweighed by 
the benefit of being able to select arbitrary data-sets for visualization.

For system tap, provided the on-disk raw trace data format is well 
defined, it will be possible to load it into SQL.  BTW, while the 
on-disk format could be XML,  there was a general feeling that XML is 
just too verbose and more compact formats intermediate forms were needed.

Can I recommend looking through the relevant slides.

>   
>> [...] What's the status of SystemTAP on the ARM?  [...]
>>     
>
> I haven't run it personally, but others have (Eugene Teo for the Nokia
> N800).  One difficulty appears to be finding a big enough ARM box to
> self-host the kernel module build process, or else cross-compiling and
> cross-running.
>   
Cool, ARM support for libunwind is currently being integrated.

Andrew