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

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Message-ID: <YB1AihrsetqhIYIc@krava>
Date:   Fri, 5 Feb 2021 13:56:42 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Namhyung Kim <namhyung@...nel.org>
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 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

> 
> I mean something like below
> 
>  __cmd_start()
> {
>     setup_server_config();
>     daemon__run();

what's daemon__run? the daemon operates in the while loop below

> 
>     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

>             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

		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