Re: [PATCH] rteval: Allow configuration from stdin

[Crystal Wood <crwood@redhat.com>]

On Thu, 2025-01-16 at 07:45 +0100, Gabriele Monaco wrote:
> 
> On Wed, 2025-01-15 at 20:14 -0500, Crystal Wood wrote:
> > On Tue, 2025-01-14 at 18:07 -0500, John Kacur wrote:
> > > Now, you wouldn't HAVE to use them, currently timerlat is the
> > > default, so if you don't specify, then it would use the default.
> > > 
> > > Like with stress-ng and the load modules, if a person tried to
> > > use a cyclictest and a timerlat option at the sametime, it should
> > > create an error and exit.
> > > 
> > > I like the above idea, because other than the optional option of
> > > --cyclictest and --timerlat, nothing else changes, so it wouldn't
> > > break anybody's scripts in any kind of major way.
> > 
> > None of these proposals should break existing scripts, assuming we
> > don't
> > change the defaults.  Removing config file support, OTOH, would force
> > people still using cyclictest to start specifying it on the command
> > line
> > one way or another.
> 
> Strictly speaking, enabling timerlat as the default measurement module
> did break existing scripts, that's what brought me to start this patch
> in the first place.

By "these proposals" I meant the command line stuff in this thread.

> 
> I agree that we should try to keep the same behaviour with respect to
> default values, no measurement module specified via command line should
> be the same as no measurement section in the config files, as
> specifying only one should disable the other. Specifying both should be
> allowed.

Why should specifying both be allowed?  We go out of our way to prevent
that, because they'll interfere with one another's latencies.

> 
> I see the command line as another setup that should override the config
> file, while behaving exactly the same (where the notation --
> measurement-modules would indeed be a bit more familiar, but I still
> like --cyclictest/--timerlat).
> 
> The order could be: command-line > explicit config file (-f) > default
> config file (/etc) > default values, this wouldn't affect the behaviour
> much.

It's not the same, since the command line would only override individual
options, while a config file replaces all defaults (at least when it
comes to enabling modules, not sure about other defaults).

> I see the simplest thing for now is to start with command-line options
> for measurement only. After we consolidate that, we can do the same for
> loads (with or without special cases).

What makes loads harder?


-Crystal