linux-kernel - Re: [PATCH 06/24] perf daemon: Add config file support

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Date:   Sat, 6 Feb 2021 17:05:04 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexei Budankov <abudankov@...wei.com>
Subject: Re: [PATCH 06/24] perf daemon: Add config file support

On Fri, Feb 5, 2021 at 9:56 PM Jiri Olsa <jolsa@...hat.com> wrote:
>
> On Fri, Feb 05, 2021 at 09:14:54PM +0900, Namhyung Kim wrote:
> > On Sun, Jan 31, 2021 at 8:49 AM Jiri Olsa <jolsa@...nel.org> wrote:
> > [SNIP]
> > > @@ -263,9 +605,16 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
> > >         signal(SIGTERM, sig_handler);
> > >
> > >         while (!done && !err) {
> > > -               if (fdarray__poll(&fda, -1)) {
> > > +               err = daemon__reconfig(daemon);
> >
> > I think it's confusing since you put the reconfig function here.
> > What not split normal and reconfig passes?
>
> hum, not sure what's confusing in here? I've been known to
> produce confusing code, but this one seems clear to me

Maybe it's because of the name.  I thought reconfig is a
special case when it detects some change.  But you call
it in the loop unconditionally.

>
> >
> > I mean something like below
> >
> >  __cmd_start()
> > {
> >     setup_server_config();
> >     daemon__run();
>
> what's daemon__run? the daemon operates in the while loop below

I thought about starting the sessions in the config.

>
> >
> >     while (!done && !err) {
> >         ...
> >         if (reconfig) {
> >             daemon__kill();
>
> you don't kill daemon for each reconfig change,
> we detect changed sessions and kill/restart only them

Yep, we can make it that way.

>
> >             setup_server_config();
> >             daemon__reconfig();
> >         }
> >     }
>
>
> so basically the current workflow is:
>
>         setup_server_config                                     <--- reads config file, prepares session objects
>
>         while (!done) {
>                 daemon__reconfig                                <--- check session objects states and run/stop them

Hmm.. then how about rename it to daemon__handle_state()
or daemon__do_loop() or something?

Thanks,
Namhyung


>
>                 if (fdarray__poll(&fda, -1)) {
>
>                         handle_config_changes(&reconfig)        <--- was there a config file change?
>
>                         if (reconfig)                           <--- yes,
>                                 setup_server_config             <---      change session objects/states
>                 }
>         }
>
> thanks,
> jirka
>