[HELP] fdo#51239 how to debug "it is slow"

[Lubos Lunak]

On Wednesday 11 of July 2012, Lionel Elie Mamane wrote:
> I'd appreciate some help on fdo#51239 which is of the form "doing this
> is horribly slow"; how can I profile LibO, i.e. find out where it
> spends all its time; if it spends a lot of time in function FOO, can I
> also get information on what the call stack looks like "most of the
> time"?

 Have a look at Callgrind (http://valgrind.org/docs/manual/cl-manual.html).

 I find it rather straightforward to use (in short: valgrind --tool=callgrind 
<app>; kcachegrind callgrind.out.<number> and keep clicking on functions in 
the 'Callees' tab), especially with the manual explaining things, but if you 
run into problems or advanced topics, feel free to ask.

> Either someone teaches me how to do it (keep in mind the "time spent"
> might be in C++ or Java code), or someone just does it and reports
> findings in the bug?

 I have no idea how Callgrind handles Java.

-- 
 Lubos Lunak
 l.lunak at suse.cz