linux-kernel - Re: [PATCH 07/11] perf session: Add __perf_session__process_dir

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Date:   Sat, 9 Mar 2019 18:21:13 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>
Subject: Re: [PATCH 07/11] perf session: Add
 __perf_session__process_dir_events function

On Fri, Mar 08, 2019 at 03:38:05PM -0300, Arnaldo Carvalho de Melo wrote:

SNIP

> > +	/* Read data from the header file.. */
> > +	ret = reader__process_events(&rd, session, &prog);
> > +	if (ret)
> > +		goto out_err;
> > +
> > +	/* ... and continue with data files. */
> > +	for (i = 0; i < data->dir.nr ; i++) {
> > +		struct perf_data_file *file = &data->dir.files[i];
> > +
> > +		if (file->size == 0)
> > +			continue;
> > +
> > +		rd = (struct reader) {
> > +			.fd		= file->fd,
> > +			.data_size	= file->size,
> > +			.data_offset	= 0,
> > +			.process	= process_index,
> > +		};
> > +
> > +		ret = reader__process_events(&rd, session, &prog);
> > +		if (ret)
> > +			goto out_err;
> 
> Don't we have to have some handling of PERF_RECORD_FINISHED_ROUND here?
> I.e. what happens if we fill th ordered events with just the contents
> of, say, the first CPU and then have those events flushed and processed
> before we start even looking at the events in the other CPUs?

PERF_RECORD_FINISHED_ROUND is disabled for directory data,
because each file contains sorted cpu data, so we only
merge them together

> 
> I think some detailed explanation of what happens here is in need, no?

right, I'll put the comment for the function

jirka