Re: perf tool: About tests debug level

[Ian Rogers <irogers@google.com>]

On Tue, Jun 22, 2021 at 4:58 AM John Garry <john.garry@huawei.com> wrote:
>
> On 22/06/2021 06:04, Ian Rogers wrote:
> >> ---- end ----
> >> Parse and process metrics: FAILED!
> >>
> >> Note that the "FAILED" messages from the test code come from pr_debug().
> >>
> >> In a way, I feel that pr_debug()/err from the test is more important
> >> than pr_debug() from the core code (when running a test).
> >>
> >> Any opinion on this or how to improve (if anyone agrees with me)? Or am
> >> I missing something? Or is it not so important?
> > Hi John,
> >
>
> Hi Ian,
>
> > I think the issue is that in the parsing you don't know it's broken
> > until something goes wrong. Putting everything on pr_err would cause
> > spam in the not broken case.
>
> Right, I would not suggest using pr_err everywhere.
>
> > Improving the parsing error handling is a
> > big task with lex and yacc to some extent getting in the way. Perhaps
> > a middle way is to have a parameter to the parser that logs more, and
> > recursively call this in the parser when parsing fails. I guess there
> > is also a danger of a performance hit.
>
> So I am thinking that for running a test, -v means different levels logs
> for test code and for core (non-test code). For example, -v prints
> pr_warn() and higher for test logs, but nothing for core logs. And then
> -vv for running a test gives pr_debug and above for test logs, and
> pr_warn and above for core logs. Or something like that.
>
> Maybe that is not a good idea. But I'm just saying that it's hard to
> debug currently at -v for tests.
>
> Thanks,
> John

I think this sounds good. It'd be nice also to have verbose output in
the shell tests following the same convention. There's currently no
verbose logging in shell tests but I propose it here:
https://lore.kernel.org/lkml/20210621215648.2991319-1-irogers@google.com/
By their nature some of the shell tests launch perf, perhaps there can
be some convention on passing the verbose flag through in those cases.

Thanks,
Ian