Re: [RFC] Open multiple trace files and, if possible, pair them

[raistlin.df@gmail.com]

Hi Stefano!

Great to see your patch here on the list! :-)

On Fri, 2021-03-05 at 07:28 +0100, Stefano De Venuto wrote:
> The goal of this patch is to teach to trace-cmd how to open multiple
> files and, if they are generated by an host and some guests, pair and
> synchronize them.
> 
> We do that by checking, for every input file, whether or not
> it has a corresponding peer, and if that's the case pairs them.
> 
Exactly. So, for the trace-devel community: our (Stefano's and mine
:-D) end goal is to do some analysis & manipulation on a combined
host+guest(s) trace file. Of course, in order to do that, we need a
nice and easy way to get such a trace file!

Implementing the support for that in trace-cmd seemed the most
reasonable first step, so we reached out and decided to work on
https://bugzilla.kernel.org/show_bug.cgi?id=211657 , which is what this
patch does.

Now ...

> We know that the code must be changed following the new API, but we
> would like to have an opinion on the work done so far.
> 
... the API is changing, so we'll have to adapt it.

Still, the patch includes, e.g., the logic for opening multiple trace
files and figuring out whether they are guest or host, etc.

And maybe these bits are still valid and you're able/willing to give us
some feedback on whether they make sense? :-)

> Signed-off-by: Stefano De Venuto <stefano.devenuto99@gmail.com>
> ---
>  tracecmd/trace-read.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
For Stefano: about the patch itself, I think the only thing I'm going
to say is that some of the lines look a bit long.

I do not see a CODING_STYLE file in the repo, but just looking around,
I got the impression that we should stay within 76-80 characters all
the times that it is possible.

And that's it, and I'm happy to let the experts speak, as I'm only
trying to learn trace-cmd internals myself. ;-D

Thanks and Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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