linux-kernel - Re: [PATCH v5 02/10] perf record: implement -f,--mmap-flush=<threshold> option

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Date:   Tue, 5 Mar 2019 13:25:41 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...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>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 02/10] perf record: implement
 -f,--mmap-flush=<threshold> option

On Fri, Mar 01, 2019 at 06:41:44PM +0300, Alexey Budankov wrote:

SNIP

> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index f3f7f3100336..9b02a68e8c23 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -334,6 +334,29 @@ static int record__aio_enabled(struct record *rec)
>  	return rec->opts.nr_cblocks > 0;
>  }
>  
> +#define MMAP_FLUSH_DEFAULT 1
> +static int record__mmap_flush_parse(const struct option *opt,
> +				    const char *str,
> +				    int unset)
> +{
> +	int mmap_len;
> +	struct record_opts *opts = (struct record_opts *)opt->value;
> +
> +	if (unset)
> +		return 0;
> +
> +	if (str)
> +		opts->mmap_flush = strtol(str, NULL, 0);
> +	if (!opts->mmap_flush)
> +		opts->mmap_flush = MMAP_FLUSH_DEFAULT;
> +
> +	mmap_len = perf_evlist__mmap_size(opts->mmap_pages);
> +	if (opts->mmap_flush > mmap_len / 4)
> +		opts->mmap_flush = mmap_len / 4;
> +

if there's point in this config option, pelase make it
configurable as the other size options we have with
the B/K/M suffixes

jirka