linux-kernel - Re: [PATCH v8 20/22] perf session: Load data directory files for analysis

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Date:   Fri, 2 Jul 2021 12:30:24 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Bayduraev <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 v8 20/22] perf session: Load data directory files for
 analysis

On Wed, Jun 30, 2021 at 06:54:59PM +0300, Alexey Bayduraev wrote:

SNIP

> +	while ((ret >= 0) && readers) {
> +		if (session_done())
> +			return 0;
> +
> +		if (rd[i].state.eof) {
> +			i = (i + 1) % session->nr_readers;
> +			continue;
> +		}
> +
> +		ret = reader__read_event(&rd[i], session, &prog);
> +		if (ret < 0)
> +			break;
> +		if (ret == READER_EOF) {
> +			ret = reader__mmap(&rd[i], session);
> +			if (ret < 0)
> +				goto out_err;
> +			if (ret == READER_EOF)
> +				readers--;
> +		}
> +
> +		/*
> +		 * Processing 10MBs of data from each reader in sequence,
> +		 * because that's the way the ordered events sorting works
> +		 * most efficiently.
> +		 */
> +		if (rd[i].state.size >= 10*1024*1024) {
> +			rd[i].state.size = 0;
> +			i = (i + 1) % session->nr_readers;
> +		}

hi,
so this was sort of hack to make this faster.. we need some
justification for this and make that configurable as well,
if we keep it

jirka