linux-kernel - Re: [PATCH v5 07/10] perf record: implement -z,--compression

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Message-ID: <20190305122622.GJ16615@krava>
Date:   Tue, 5 Mar 2019 13:26:22 +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 07/10] perf record: implement -z,--compression_level=n
 option and compression

On Fri, Mar 01, 2019 at 06:58:32PM +0300, Alexey Budankov wrote:

SNIP

> +static size_t record__process_comp_header(void *record, size_t increment)
> +{
> +	struct compressed_event *event = record;
> +	size_t size = sizeof(struct compressed_event);
> +
> +	if (increment) {
> +		event->header.size += increment;
> +		return increment;
> +	} else {
> +		event->header.type = PERF_RECORD_COMPRESSED;
> +		event->header.size = size;
> +		return size;
> +	}

so zstd_compress_stream_to_records calls this in the loop:

          while (input.pos < input.size) {
	  	...
                size = process_header(record, 0);
		...
                size = process_header(record, size);
	}

the header.size will get overwritten with every new iteration, no?

jirka