linux-kernel - Re: [PATCH v3 6/8] perf session: Move event read code to separate function

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Date:   Fri, 8 Oct 2021 16:38:50 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Bayduraev, Alexey V" <alexey.v.bayduraev@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Alexei Budankov <abudankov@...wei.com>,
        Riccardo Mancini <rickyman7@...il.com>
Subject: Re: [PATCH v3 6/8] perf session: Move event read code to separate
 function

On Fri, Oct 08, 2021 at 11:42:18AM +0300, Bayduraev, Alexey V wrote:
> 
> 
> On 08.10.2021 10:33, Jiri Olsa wrote:
> > On Thu, Oct 07, 2021 at 01:25:41PM +0300, Alexey Bayduraev wrote:
> > 
> > SNIP
> > 
> >>  static int
> >> -reader__process_events(struct reader *rd, struct perf_session *session,
> >> -		       struct ui_progress *prog)
> >> +reader__read_event(struct reader *rd, struct perf_session *session,
> >> +		   struct ui_progress *prog)
> >>  {
> >>  	u64 size;
> >>  	int err = 0;
> >>  	union perf_event *event;
> >>  	s64 skip;
> >>  
> >> -	err = reader__init(rd, &session->one_mmap);
> >> -	if (err)
> >> -		goto out;
> >> -
> >> -remap:
> >> -	err = reader__mmap(rd, session);
> >> -	if (err)
> >> -		goto out;
> >> -
> >> -more:
> >>  	event = fetch_mmaped_event(rd->head, rd->mmap_size, rd->mmap_cur,
> >>  				   session->header.needs_swap);
> >>  	if (IS_ERR(event))
> >>  		return PTR_ERR(event);
> >>  
> >>  	if (!event)
> >> -		goto remap;
> >> +		return 1;
> >>  
> >>  	session->active_decomp = &rd->decomp_data;
> >>  	size = event->header.size;
> >> @@ -2311,6 +2301,33 @@ reader__process_events(struct reader *rd, struct perf_session *session,
> >>  
> >>  	ui_progress__update(prog, size);
> >>  
> >> +out:
> >> +	session->active_decomp = &session->decomp_data;
> >> +	return err;
> >> +}
> >> +
> >> +static int
> >> +reader__process_events(struct reader *rd, struct perf_session *session,
> >> +		       struct ui_progress *prog)
> >> +{
> >> +	int err;
> >> +
> >> +	err = reader__init(rd, &session->one_mmap);
> >> +	if (err)
> >> +		goto out;
> >> +
> >> +remap:
> >> +	err = reader__mmap(rd, session);
> >> +	if (err)
> >> +		goto out;
> >> +
> >> +more:
> >> +	err = reader__read_event(rd, session, prog);
> >> +	if (err < 0)
> >> +		goto out;
> >> +	else if (err == 1)
> >> +		goto remap;
> >> +
> >>  	if (session_done())
> >>  		goto out;
> >>  
> >> @@ -2318,7 +2335,6 @@ reader__process_events(struct reader *rd, struct perf_session *session,
> >>  		goto more;
> >>  
> >>  out:
> >> -	session->active_decomp = &session->decomp_data;
> > 
> > active_decomp should be set/unset within reader__process_events,
> > not just for single event read, right?
> 
> No, it should be set before perf_session__process_event/process_decomp_events
> and unset after these calls. So active_decomp setting/unsetting is moved in
> this patch to the reader__read_event function. This is necessary for multiple
> trace reader because it could call reader__read_event in round-robin manner.

hum, is that code already in? I can't see this happening in current code

jirka

> 
> Regards,
> Alexey
> 
> > 
> > jirka
> > 
> >>  	return err;
> >>  }
> >>  
> >> -- 
> >> 2.19.0
> >>
> > 
>